|
<head data-webtasks-id="8f58fc5c-481b-4f6f"><style data-merge-styles="true" data-webtasks-id="e3d7bf6b-c474-47bc"></style><style data-merge-styles="true" data-webtasks-id="47a0173d-4da8-470c"></style><style data-merge-styles="true" data-webtasks-id="051655fe-f85f-4198"></style><meta charset="utf-8" data-webtasks-id="c132f59c-2887-435c"><meta name="title" content="Encyclopedia.com | Free Online Encyclopedia" data-webtasks-id="ae72c111-f297-4d26"><link rel="shortlink" href="https://www.encyclopedia.com/" data-webtasks-id="dc4a4041-2cbb-47f3"><link rel="canonical" href="https://www.encyclopedia.com/" data-webtasks-id="593e9849-e146-43f5"><meta name="description" content="Encyclopedia.com – Online dictionary and encyclopedia with pictures, facts, and videos. Get information and homework help with millions of articles in our FREE, online library." data-webtasks-id="9a975e7d-133d-4b7b"><meta name="abstract" content="Encyclopedia.com – Online dictionary and encyclopedia with pictures, facts, and videos. Get information and homework help with millions of articles in our FREE, online library." data-webtasks-id="fbf24ec7-7060-4692"><meta name="keywords" content="Encyclopedia, Online, dictionary, and, encyclopedia, pictures, facts, and, videos, Get, information, and, homework, help, millions, articles, our, FREE, online, library" data-webtasks-id="1c954a87-40ba-4b70"><meta name="Generator" content="Drupal 8 (https://www.drupal.org)" data-webtasks-id="eba39b5b-ff87-406c"><meta name="MobileOptimized" content="width" data-webtasks-id="aebd4da0-3f0f-49bf"><meta name="HandheldFriendly" content="true" data-webtasks-id="06fe1174-49bd-468d"><meta name="viewport" content="width=device-width, initial-scale=1, minimum-scale=1, maximum-scale=1, user-scalable=0" data-webtasks-id="a8e87b43-7959-4646"><link rel="shortcut icon" href="/sites/default/files/favicon.ico" type="image/vnd.microsoft.icon" data-webtasks-id="0a10c946-dad7-4e61"><link rel="alternate" type="application/rss+xml" title="" href="http://www.encyclopedia.com/rss.xml" data-webtasks-id="f7bd0822-8cea-425b"><title data-webtasks-id="3552e192-b58f-4e43">Encyclopedia.com | Free Online Encyclopedia</title> <script async="" defer="" src="https://launchpad.privacymanager.io/latest/launchpad.bundle.js" data-webtasks-id="86bbb3fa-4243-42c8"></script><script type="text/javascript" src="https://launchpad-wrapper.privacymanager.io/69e75073-3763-483e-a64c-0d281bfd9225/launchpad-liveramp.js" data-webtasks-id="b682dd63-3073-40ea"></script><script type="text/javascript" async="" src="https://collector.brandmetrics.com/c.js?siteid=f9816ecc-b51b-4747-bc3e-1ea86a0677a2&toploc=www.encyclopedia.com&rnd=739138" data-webtasks-id="b238913e-0c94-4993"></script><script async="" src="//cdn.confiant-integrations.net/gptprebidnative/202304111045/wrap.js" data-webtasks-id="adab72bb-8c8f-4518"></script><script type="text/javascript" src="https://cdn.brandmetrics.com/tag/aa466d868b2742ffa2cc31bb6341dc12/cafemedia.js" data-webtasks-id="0a26491e-e27a-4a76"></script><script type="text/javascript" src="https://cdn.confiant-integrations.net/mOinGM9MTu5v-Lto835XLhlrSPY/gpt_and_prebid/config.js" data-webtasks-id="345c1188-786f-4013"></script><script type="text/javascript" src="https://sb.scorecardresearch.com/beacon.js" data-webtasks-id="58321665-8ab4-40de"></script><script type="text/javascript" src="https://unpkg.com/[email protected]/dist/web-vitals.umd.js" defer="" data-webtasks-id="47a6acc5-75ef-4965"></script><script src="https://ads.adthrive.com/builds/customizations/5dc336ff22eddf534ab4417c.js" data-webtasks-id="9a8cd4da-58fd-4232"></script><script src="https://ads.adthrive.com/builds/core/e1eb55f/es2018/js/adthrive.min.js?deployment=2023-07-06-5:adm-929:pr3555:e1eb55f&bucket=flex-28&deliveryFeatures=rubiconFloors,recencyFrequency,ttdSync,reissuingSticky,manualCookieSync,prebidLoad,gptLoad,amazonLoad&siteid=5dc336ff22eddf534ab4417c" data-webtasks-id="ba3c9955-4127-4c98"></script><script src="https://ads.adthrive.com/builds/core/e1eb55f/vendor/prebid/es2018/prebid.min.js" data-webtasks-id="f9ec34de-d9b5-4f51"></script><script src="https://securepubads.g.doubleclick.net/tag/js/gpt.js" data-webtasks-id="d3890232-633d-4001"></script><script src="https://c.amazon-adsystem.com/aax2/apstag.js" data-webtasks-id="307adb8c-660d-44b6"></script><script type="text/javascript" async="" src="https://www.googletagmanager.com/gtag/js?id=G-VTWQL8EHT3&l=dataLayer&cx=c" data-webtasks-id="b0974c48-4b31-4960"></script><script async="" src="https://ads.adthrive.com/sites/5dc336ff22eddf534ab4417c/ads.min.js?referrer=https%3A%2F%2Fwww.encyclopedia.com%2F" data-webtasks-id="544f9495-9526-4914"></script><script async="" src="https://www.google-analytics.com/analytics.js" data-webtasks-id="ab3f220c-9d3f-42bf"></script><script async="" src="https://www.googletagmanager.com/gtm.js?id=GTM-W4GBLXB" data-webtasks-id="9d3a8011-22e2-4d6f"></script><script type="text/javascript" data-webtasks-id="d6039f6e-e0f8-456a"> |
|
(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){ |
|
(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o), |
|
m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m) |
|
})(window,document,'script','https://www.google-analytics.com/analytics.js','ga'); |
|
ga('create', 'UA-64847704-1', 'auto'); |
|
ga('send', 'pageview'); |
|
</script> <script data-cfasync="false" data-webtasks-id="3a9d5905-0f44-4f1e">(function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start': |
|
new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0], |
|
j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src= |
|
'https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f); |
|
})(window,document,'script','dataLayer','GTM-W4GBLXB');</script> <script type="text/javascript" data-webtasks-id="b231d460-bc5b-44b2">(function(w, d) { |
|
w.adthrive = w.adthrive || {}; |
|
w.adthrive.cmd = w.adthrive.cmd || []; |
|
w.adthrive.plugin = 'adthrive-ads-1.0.41-manual'; |
|
w.adthrive.host = 'ads.adthrive.com'; |
|
var s = d.createElement('script'); |
|
s.async = true; |
|
s.referrerpolicy='no-referrer-when-downgrade'; |
|
s.src = 'https://' + w.adthrive.host + '/sites/5dc336ff22eddf534ab4417c/ads.min.js?referrer=' + w.encodeURIComponent(w.location.href); |
|
var n = d.getElementsByTagName('script')[0]; |
|
n.parentNode.insertBefore(s, n); |
|
})(window, document);</script><link rel="stylesheet" media="all" href="/sites/default/files/css/css_AxrMp2NNpMECnjp7kzTMN0neY6nPkuzEFUTf02NmHtU.css" data-webtasks-id="95caeb8b-2bcb-4033"><link rel="stylesheet" media="all" href="/sites/default/files/css/css_PKoD1c51rXhDWjoL2z3EIsRnpif7i9DxnaRGocb8JzA.css" data-webtasks-id="db1f0d50-9ca0-412f"><link rel="stylesheet" media="all" href="/sites/default/files/css/css_k9u1IODySqC3j4I1pBBMqRSLt5ZKAL5HHw12USc5C1U.css" data-webtasks-id="afad666a-1e9c-480c"> <script type="text/javascript" data-webtasks-id="e0d39d61-29a1-4c56"> |
|
var _reportClientErrors = false; |
|
var nodeType = "", |
|
rootPath = ""; |
|
var dataLayer = [{ |
|
pageType : 'home', |
|
}]; |
|
</script><style type="text/css" data-webtasks-id="cd72cff7-fb8c-471f">.adthrive-ad{margin-top:10px;margin-bottom:10px;text-align:center;overflow-x:visible;clear:both;line-height:0}</style><style type="text/css" data-webtasks-id="64de8fd7-2532-4f08">.adthrive-ccpa-modal{background-color:#000;background-color:rgba(0,0,0,.4);display:none;height:100%;left:0;overflow:auto;position:fixed;top:0;width:100%;z-index:2147483647}.adthrive-ccpa-modal-content{background-color:#fefefe;border:1px solid #888;border-radius:10px;box-shadow:0 0 10px rgba(0,0,0,.5);font-family:Verdana,Geneva,Tahoma,sans-serif;margin:0 auto;max-width:592px;padding:20px 24px 24px;position:relative;top:50%;transform:translateY(-50%);width:80%}#adthrive-ccpa-modal-title{color:rgba(0,0,0,.87);font-size:20px;line-height:26px}.adthrive-ccpa-modal-btn:focus,.adthrive-ccpa-modal-btn:hover{color:#000;cursor:pointer;text-decoration:none}#adthrive-ccpa-modal-language{color:rgba(0,0,0,.87);display:block;font-size:14px;line-height:20px;margin:16px 0 32px}#adthrive-ccpa-modal-cancel-btn:focus,#adthrive-ccpa-modal-cancel-btn:hover,#adthrive-ccpa-modal-close-btn-container:focus,#adthrive-ccpa-modal-close-btn-container:hover{color:rgba(0,0,0,.8);cursor:pointer;text-decoration:none}#adthrive-ccpa-modal-continue-btn:focus,#adthrive-ccpa-modal-continue-btn:hover{color:hsla(0,0%,100%,.8);cursor:pointer;text-decoration:none}#adthrive-ccpa-modal-close-btn-container{color:#000;font-size:20px;font-weight:700;line-height:20px;position:absolute;right:8px;top:8px}.adthrive-ccpa-lower-buttons-container{color:#000;font-size:18px}#adthrive-ccpa-modal-cancel-btn{display:inline-block;text-align:left;width:calc(100% - 150px)}#adthrive-ccpa-modal-continue-btn{background-color:#010044;border-radius:10px;color:#fff;display:inline-block;height:44px;line-height:44px;text-align:center;width:150px}@media screen and (max-width:896px){.adthrive-ccpa-modal-content{margin:0 auto;position:relative;width:calc(100% - 80px)}#adthrive-ccpa-modal-title{font-size:16px;line-height:24px}#adthrive-ccpa-modal-language{font-size:12px;line-height:16px;text-align:left}.adthrive-ccpa-lower-buttons-container{font-size:14px}#adthrive-ccpa-modal-close-btn-container{font-size:14px;line-height:14px}}@media screen and (max-width:350px){#adthrive-ccpa-modal-title{font-size:14px;line-height:24px}#adthrive-ccpa-modal-language{font-size:10px;line-height:14px;text-align:left}.adthrive-ccpa-lower-buttons-container{display:block;font-size:12px;text-align:center;width:100%}#adthrive-ccpa-modal-close-btn-container{display:block;font-size:12px;line-height:12px}#adthrive-ccpa-modal-cancel-btn,#adthrive-ccpa-modal-continue-btn{display:block;text-align:center;width:100%}#adthrive-ccpa-modal-cancel-btn{margin-bottom:10px}}</style><style type="text/css" data-webtasks-id="f99fe9ab-eacb-489b">.adthrive-ad{clear:both;line-height:0;margin-bottom:10px;margin-top:10px;overflow-x:visible;text-align:center}.adthrive-ad-cls{align-items:center;display:flex;flex-wrap:wrap;justify-content:center}.adthrive-ad-cls>div,.adthrive-ad-cls>iframe{flex-basis:100%}.adthrive-interstitial{margin-bottom:0;margin-top:0}.adthrive-native-recipe{display:inline-block}.adthrive-recipe{min-width:300px}.adthrive-device-desktop .adthrive-recipe,.adthrive-device-tablet .adthrive-recipe{max-width:320px}.adthrive-stuck.adthrive-sticky.adthrive-header,.adthrive-stuck.adthrive-sticky.adthrive-sidebar{position:fixed;top:0;z-index:9999}.adthrive-stuck.adthrive-header{margin-top:0}.adthrive-sticky-sidebar{align-items:center;display:flex;flex-direction:column;justify-content:flex-start;margin:10px 0;min-height:1200px!important;padding-bottom:0;position:relative}.adthrive-sticky-sidebar div{flex-basis:unset;position:sticky;top:5px}.adthrive-sticky.adthrive-footer{background-color:hsla(0,0%,100%,.8);border-top:2px solid hsla(0,0%,88%,.8);bottom:0;box-sizing:content-box;left:0;margin:0;max-height:100px;overflow:hidden;position:fixed;text-align:center;width:100%;z-index:1000001}.adthrive-sticky.adthrive-footer>.adthrive-close{background:#fff;border:1px solid #b2b2b2;border-radius:20px;color:#b2b2b2;cursor:pointer;display:inline-block;font-family:arial,sans-serif;font-size:20px;line-height:20px;padding:0 5px;position:absolute;right:5px;top:5px}.adthrive-device-desktop .adthrive-sticky.adthrive-footer>.adthrive-close{right:10px;top:10px}.adthrive-ccpa-link,.adthrive-footer-message,.adthrive-privacy-preferences{margin-top:5px;text-align:center}.adthrive-footer>div,.adthrive-header>div{max-width:1200px}#next-video,#stay-video{background-color:#333;color:#fff;cursor:pointer;height:40px;line-height:40px;margin:10px;opacity:.9;text-align:center;width:100px}#next-video{box-shadow:inset 0 0 0 0 #333;transition:box-shadow 5s linear}#next-stay-container.loaded #next-video{box-shadow:inset 100px 0 0 0 red}.jw-flag-small-player #next-video,.jw-flag-small-player #stay-video{height:30px;line-height:30px;width:75px}#next-stay-container{bottom:25%;margin:12px;position:absolute;right:0}.jw-flag-small-player #next-stay-container{margin:0}.video-box-shadow{box-shadow:0 0 10px rgba(0,0,0,.5)}.adthrive-wrapper-bar{background-color:#595959;border-top-left-radius:5px;border-top-right-radius:5px;display:none;font-family:Arial,Helvetica,sans-serif;height:36px}.adthrive-video-title{color:#fff;font-size:13px;font-weight:700;text-decoration:none}.adthrive-wrapper-title-wrapper{align-items:center;display:inline-flex;justify-content:center;margin-left:10px;margin-right:10px;min-width:0}.adthrive-wrapper-title-wrapper>a>svg,.adthrive-wrapper-title-wrapper>div>svg{fill:#fff;margin-right:5px;vertical-align:middle}.adthrive-wrapper-title-wrapper>a{text-decoration:none}.adthrive-video-text-cutoff{color:#fff;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.adthrive-collapse-player{border-bottom:1px solid #dbdbdb;border-top:1px solid #dbdbdb;margin-left:auto;margin-right:auto;padding:8px!important;width:90%}.adthrive-outstream-container{flex-basis:unset!important;margin:0 auto;position:relative}.adthrive-player-idle{display:none;transition:all .5s ease-out;transition-delay:.5s}.adthrive-player-playing{display:block;transition:all .5s ease-in;transition-delay:.5s}.adthrive-sticky-outstream-active.adthrive-new-outstream-player{animation-duration:.5s;animation-iteration-count:1;animation-name:adthrive-fade-in;animation-timing-function:ease-in;opacity:1}.adthrive-sticky-outstream-idle.adthrive-new-outstream-player{animation-duration:.5s;animation-iteration-count:1;animation-name:adthrive-fade-out;animation-timing-function:ease-out;display:block;opacity:0}@keyframes adthrive-fade-in{0%{opacity:0}to{opacity:1}}@keyframes adthrive-fade-out{0%{opacity:1}to{opacity:0}}.adthrive-player-ad-controls-play,.adthrive-player-ad-controls-volume{display:inline-block;margin-top:-8px;padding:8px 0 0}.adthrive-player-icon{cursor:pointer;display:inline-block;margin:0 10px!important}.adthrive-player-icon-hidden{display:none}.adthrive-player-icon svg{filter:drop-shadow(3px 5px 3px rgb(0 0 0/.5));pointer-events:none}.adthrive-player-ad-container{bottom:0;margin:0;position:absolute}.adthrive-sticky-outstream.adthrive-sticky-outstream-mobile .adthrive-player-ad-container{margin-bottom:2px;margin-top:2px}.adthrive-player-ad-controls{bottom:6px;height:26px;left:0;line-height:18px;padding:0;position:absolute;text-align:left;width:100%;z-index:1000000}.adthrive-player-volume-control{height:30px;left:6px;margin:0!important;position:absolute;top:-66px;transform:rotate(-90deg);width:100px;z-index:10000}.adthrive-player-volume-control input[type=range]{-webkit-appearance:none;background-color:#777;border:0;border-radius:20px;height:10px;margin:6px 6px 0;outline:0;overflow:hidden;padding:0;vertical-align:bottom;width:100px}.adthrive-player-volume-control input[type=range]::-webkit-slider-runnable-track{-webkit-appearance:none;color:#777;height:10px;margin-top:-1px}.adthrive-player-volume-control input[type=range]::-webkit-slider-thumb{-webkit-appearance:none;background:#fff;border-radius:50%;box-shadow:-325px 0 0 320px #ccc,inset 0 0 0 40px #fff;cursor:pointer;height:10px;position:relative;width:10px}.adthrive-player-volume-control input[type=range]:active::-webkit-slider-thumb{background:#fff;box-shadow:-325px 0 0 320px #ddd,inset 0 0 0 3px #fff}.adthrive-player-volume-control input[type=range]::-moz-range-progress{background-color:#ddd;box-shadow:-325px 0 0 320px #ddd,inset 0 0 0 3px #ddd}.adthrive-player-volume-control input[type=range]::-moz-range-track{background-color:#777}.adthrive-player-volume-control input[type=range]::-ms-fill-lower{background-color:#ddd;box-shadow:-325px 0 0 320px #ddd,inset 0 0 0 3px #ddd}.adthrive-player-volume-control input[type=range]::-ms-fill-upper{background-color:#777}.adthrive-player-position.adthrive-collapse-float{position:fixed;width:300px;z-index:2147483644}.adthrive-player-position.adthrive-collapse-float.adthrive-collapse-right{right:5px;top:0}.adthrive-player-position.adthrive-collapse-float.adthrive-collapse-bottom-right{bottom:100px;right:5px}.adthrive-player-position.adthrive-collapse-float.adthrive-collapse-bottom-left{bottom:100px;left:5px}.adthrive-player-position.adthrive-collapse-float>.adthrive-player-title{display:none}.adthrive-player-position.adthrive-collapse-sticky{padding-bottom:20px;padding-top:20px;position:fixed;z-index:9999}.adthrive-player-position.adthrive-collapse-sticky>.adthrive-player-title{display:none}.adthrive-collapse-mobile-background{background-color:#000;left:0;position:fixed;top:0;z-index:99990}.adthrive-top-collapse-close{left:-30px;position:fixed;top:5px;z-index:1}.adthrive-sticky-outstream-top-center>.adthrive-top-collapse-close{left:10px;position:fixed;top:48px}.adthrive-sticky-outstream-top-center.adthrive-sticky-outstream-mobile>.adthrive-top-collapse-close{top:10px}.adthrive-top-collapse-wrapper-bar>* .adthrive-top-collapse-close{left:0;position:relative;top:0}.adthrive-top-collapse-wrapper-bar>* .adthrive-wrapper-float-close{display:none;float:none;margin-bottom:0}.adthrive-player-position.adthrive-collapse-mobile{position:fixed;width:300px;z-index:99998}.adthrive-player-position.adthrive-collapse-mobile.adthrive-collapse-medium,.adthrive-player-position.adthrive-collapse-mobile.adthrive-collapse-small{width:272px}.adthrive-player-position.adthrive-collapse-mobile.adthrive-collapse-top-right{right:10px;top:26px}.adthrive-player-position.adthrive-collapse-mobile.adthrive-collapse-top-left{left:5px;top:26px}.adthrive-player-position.adthrive-collapse-mobile.adthrive-collapse-bottom-left{bottom:52px;left:5px}.adthrive-player-position.adthrive-collapse-mobile.adthrive-collapse-bottom-right{bottom:52px;right:10px}.adthrive-player-position.adthrive-collapse-mobile>.adthrive-player-title{display:none}.adthrive-player-position.adthrive-collapse-mobile.adthrive-collapse-top-center>.adthrive-wrapper-bar{display:none!important}.adthrive-player-position.adthrive-collapse-mobile.adthrive-collapse-top-center>.adthrive-top-collapse-wrapper-bar{display:block}.adthrive-player-position.adthrive-collapse-mobile.adthrive-collapse-top-center.adthrive-player-without-wrapper-text{left:50%;padding-bottom:5px;padding-top:5px;top:0;transform:translateX(-50%)}.adthrive-player-position.adthrive-collapse-mobile.adthrive-collapse-top-center.adthrive-player-with-wrapper-text{padding-bottom:5px;padding-top:5px;right:5px;top:0}.adthrive-top-collapse-wrapper-bar{color:#fff;display:none;left:5px;padding-bottom:5px;padding-top:5px;position:fixed;top:0;width:-webkit-calc(100% - 282px);width:-moz-calc(100% - 282px);width:calc(100% - 282px);z-index:99998}.adthrive-top-collapse-wrapper-video-title{-webkit-line-clamp:3;line-clamp:3;-webkit-box-orient:vertical;color:#fff;display:-webkit-box;font-size:13px;font-weight:700;line-height:1.2;overflow:hidden;text-decoration:none;text-overflow:ellipsis}.adthrive-top-collapse-wrapper-bar a a.adthrive-learn-more-link{color:#fff;display:inline-block;font-size:13px;line-height:1.2}h3.adthrive-player-title{margin:10px 0}.adthrive-wrapper-close{align-items:center;color:#fff;font-size:36px;height:36px;justify-content:center;margin-left:auto;margin-right:0;min-width:36px}.adthrive-wrapper-float-close{cursor:pointer;display:none;float:right;margin-bottom:5px}.adthrive-top-left-outer{height:78px;left:-30px;position:absolute;top:-55px;width:78px}.adthrive-top-left-outer>svg{bottom:30px;left:30px;position:absolute}.adthrive-top-left-inner{position:absolute;top:0}.adthrive-top-left-inner.adthrive-wrapper-float-close{background:rgba(0,0,0,.5);color:#fff;padding:2px;pointer-events:none;width:100%;z-index:99}.adthrive-new-outstream-player .adthrive-top-left-inner.adthrive-wrapper-float-close{z-index:10000}.adthrive-new-outstream-player .adthrive-ad{margin-bottom:0;margin-top:0}.adthrive-top-left-inner-wrapper.adthrive-wrapper-float-close{background:rgba(0,0,0,.5);color:#fff;padding:2px;pointer-events:none;position:absolute;top:36px;width:100%;z-index:10000}.adthrive-sticky-outstream>.adthrive-wrapper-float-close{position:absolute;right:1px;top:32px}.adthrive-sticky-outstream>.adthrive-wrapper-float-close.adthrive-wrapper-close-outside-left{left:2px}.adthrive-sticky-outstream>.adthrive-wrapper-float-close.adthrive-wrapper-close-bkgd-50{background:rgba(0,0,0,.5);color:#fff;left:0;padding:2px;pointer-events:none;top:52px}.adthrive-new-outstream-player{margin-bottom:20px;padding:0!important}.adthrive-new-outstream-player>.adthrive-wrapper-float-close.adthrive-wrapper-close-bkgd-50{top:0}.adthrive-wrapper-close-bkgd-50>#adthrive-sticky-outstream-close{padding:2px 0 0 2px;pointer-events:all}.adthrive-sticky-outstream{display:none;overflow:hidden;padding-top:20px;position:fixed;z-index:2147483644}.adthrive-sticky-outstream.adthrive-sticky-outstream-mobile{bottom:52px;right:10px}.adthrive-sticky-outstream.adthrive-sticky-outstream-active.adthrive-sticky-outstream-top-center{background:#000;bottom:auto;left:0;right:0;top:0;transform:none}.adthrive-sticky-outstream.adthrive-sticky-outstream-desktop{bottom:100px;right:5px}.adthrive-sticky-outstream.adthrive-sticky-outstream-top-center.adthrive-sticky-outstream-desktop,.adthrive-sticky-outstream.adthrive-sticky-outstream-top-center.adthrive-sticky-outstream-mobile{bottom:auto}.adthrive-sticky-outstream.adthrive-sticky-outstream-top-center.adthrive-sticky-outstream-mobile .adthrive-stickyoutstream-container{margin:0 auto}.adthrive-sticky-outstream.adthrive-sticky-outstream-active{display:block}.adthrive-video-stickyoutstream div:first-of-type{margin:-1px}.adthrive-video-stickyoutstream-new-player div:first-of-type{margin:0}.adthrive-instream-close{pointer-events:all}.adthrive-instream-close.adthrive-float-left{float:left}.adthrive-ccpa-link,.adthrive-ccpa-link span,.adthrive-footer-message span,.adthrive-privacy-preferences a{color:#a9a9a9;font-family:Arial,Helvetica Neue,Helvetica,sans-serif;font-size:13px}.adthrive-ccpa-link a{cursor:pointer;text-decoration:underline}.adthrive-device-phone .adthrive-footer-message{margin-bottom:60px}.adthrive-footer-message{margin-bottom:100px}.adthrive-footer-message>span{border-top:1px solid #b2b2b2;padding-top:5px;text-transform:uppercase}.adthrive-parallax-slot{height:400px;overflow:hidden;padding-top:5px}.adthrive-parallax-ad{transform:translateY(0);transition:transform .3s ease-out}.adthrive-sticky-container.adthrive-parallax-slot{flex-direction:row;justify-content:center;padding-top:10px}#_inv_voicefive___{display:none}</style><meta http-equiv="origin-trial" content="A7CQXglZzTrThjGTBEn1rWTxHOEtkWivwzgea+NjyardrwlieSjVuyG44PkYgIPGs8Q9svD8sF3Yedn0BBBjXAkAAACFeyJvcmlnaW4iOiJodHRwczovL2RvdWJsZWNsaWNrLm5ldDo0NDMiLCJmZWF0dXJlIjoiUHJpdmFjeVNhbmRib3hBZHNBUElzIiwiZXhwaXJ5IjoxNjk1MTY3OTk5LCJpc1N1YmRvbWFpbiI6dHJ1ZSwiaXNUaGlyZFBhcnR5Ijp0cnVlfQ==" data-webtasks-id="720bd219-dee7-4291"><meta http-equiv="origin-trial" content="A3vKT9yxRPjmXN3DpIiz58f5JykcWHjUo/W7hvmtjgh9jPpQgem9VbADiNovG8NkO6mRmk70Kex8/KUqAYWVWAEAAACLeyJvcmlnaW4iOiJodHRwczovL2dvb2dsZXN5bmRpY2F0aW9uLmNvbTo0NDMiLCJmZWF0dXJlIjoiUHJpdmFjeVNhbmRib3hBZHNBUElzIiwiZXhwaXJ5IjoxNjk1MTY3OTk5LCJpc1N1YmRvbWFpbiI6dHJ1ZSwiaXNUaGlyZFBhcnR5Ijp0cnVlfQ==" data-webtasks-id="adc6b577-2577-4dcb"><meta http-equiv="origin-trial" content="A4A26Ymj79UVY7C7JGUS4BG1s7MdcDokAQf/RP0paks+RoTYbXHxceT/5L4iKcsleFCngi75YfNRGW2+SpVv1ggAAACLeyJvcmlnaW4iOiJodHRwczovL2dvb2dsZXRhZ3NlcnZpY2VzLmNvbTo0NDMiLCJmZWF0dXJlIjoiUHJpdmFjeVNhbmRib3hBZHNBUElzIiwiZXhwaXJ5IjoxNjk1MTY3OTk5LCJpc1N1YmRvbWFpbiI6dHJ1ZSwiaXNUaGlyZFBhcnR5Ijp0cnVlfQ==" data-webtasks-id="a5ff6035-6088-4258"><meta http-equiv="origin-trial" content="As0hBNJ8h++fNYlkq8cTye2qDLyom8NddByiVytXGGD0YVE+2CEuTCpqXMDxdhOMILKoaiaYifwEvCRlJ/9GcQ8AAAB8eyJvcmlnaW4iOiJodHRwczovL2RvdWJsZWNsaWNrLm5ldDo0NDMiLCJmZWF0dXJlIjoiV2ViVmlld1hSZXF1ZXN0ZWRXaXRoRGVwcmVjYXRpb24iLCJleHBpcnkiOjE3MTk1MzI3OTksImlzU3ViZG9tYWluIjp0cnVlfQ==" data-webtasks-id="5577dbd0-d4a5-4012"><meta http-equiv="origin-trial" content="AgRYsXo24ypxC89CJanC+JgEmraCCBebKl8ZmG7Tj5oJNx0cmH0NtNRZs3NB5ubhpbX/bIt7l2zJOSyO64NGmwMAAACCeyJvcmlnaW4iOiJodHRwczovL2dvb2dsZXN5bmRpY2F0aW9uLmNvbTo0NDMiLCJmZWF0dXJlIjoiV2ViVmlld1hSZXF1ZXN0ZWRXaXRoRGVwcmVjYXRpb24iLCJleHBpcnkiOjE3MTk1MzI3OTksImlzU3ViZG9tYWluIjp0cnVlfQ==" data-webtasks-id="2fdfebd5-60ad-4570"><script src="https://securepubads.g.doubleclick.net/pagead/managed/js/gpt/m202306280101/pubads_impl.js" async="" data-webtasks-id="8c03f4c0-791d-4acd"></script><link rel="stylesheet" type="text/css" href="https://ads.adthrive.com/sites/5dc336ff22eddf534ab4417c/ads.min.css" data-webtasks-id="d1c848f1-816b-487d"><script src="https://cdn-ima.33across.com/ima.js" data-webtasks-id="94946276-20bf-4b86"></script><script src="//cdn.id5-sync.com/api/1.0/id5-api.js" data-webtasks-id="c1710d4d-716d-4dfe"></script><iframe name="cnftComm" data-webtasks-id="dea8a427-bbf6-4738" style="display: none;"></iframe></head><body class="path-frontpage adthrive-device-desktop" data-webtasks-id="660d233d-f40b-43df"> <noscript data-webtasks-id="cf6a504b-0914-4249"><iframe src="https://www.googletagmanager.com/ns.html?id=GTM-W4GBLXB" |
|
height="0" width="0" style="display:none;visibility:hidden"></iframe></noscript> <a href="#main-content" class="visually-hidden focusable" data-webtasks-id="e8eb3b4e-d6fc-4c42"> Skip to main content </a> <header data-webtasks-id="92332b93-1121-4017"><div class="container" data-webtasks-id="c1d8ea1c-34c6-4ab6"><div class="row" data-webtasks-id="c95fcd94-f835-4456"><div class="col align-items-center d-flex" data-webtasks-id="9fea912b-d3ef-47db"><div style="visibility: hidden; position: absolute; width: 0; height: 0;" data-webtasks-id="b2ae4260-3fb2-43f7"> <svg xmlns="http://www.w3.org/2000/svg" data-webtasks-id="65b27ca3-5d11-436a"> <symbol id="encyclopedia-logo" data-webtasks-id="2f88a4c3-03b1-4345"> <path fill="#00428b" d="M0 5.36h11.54v3.38h-7.6v2.16h6.88v3.14H3.94v2.27h7.7v3.38H0zM13.66 5.36h3.7l5.9 7.57V5.35h3.94V19.7h-3.48l-6.12-7.86v7.86h-3.94zM36.13 19.98a7.55 7.55 0 01-2.89-.55 7.06 7.06 0 01-2.34-1.55 7.46 7.46 0 01-2.16-5.31v-.05a7.49 7.49 0 012.15-5.3 7.2 7.2 0 012.39-1.58 7.81 7.81 0 013.02-.58 8.66 8.66 0 012 .22 6.87 6.87 0 011.65.62 6.6 6.6 0 011.35.95 7.88 7.88 0 011.08 1.2l-3 2.32a5.16 5.16 0 00-1.34-1.23 3.35 3.35 0 00-1.79-.45 3.18 3.18 0 00-1.38.3 3.31 3.31 0 00-1.07.81 3.8 3.8 0 00-.7 1.2 4.24 4.24 0 00-.26 1.48v.04a4.39 4.39 0 00.25 1.5 3.77 3.77 0 00.71 1.23 3.3 3.3 0 001.08.8 3.18 3.18 0 001.38.3 3.92 3.92 0 001.01-.12 3.1 3.1 0 00.84-.36 4.6 4.6 0 00.72-.55 8.37 8.37 0 00.67-.7l2.99 2.13a10.63 10.63 0 01-1.12 1.29A6.41 6.41 0 0140 19.06a7.18 7.18 0 01-1.72.68 8.59 8.59 0 01-2.15.24zM47.8 14.33l-5.44-8.98h4.53l2.94 5.23 2.97-5.23h4.45l-5.45 8.91v5.43h-4zM64.87 19.98a7.55 7.55 0 01-2.89-.55 7.07 7.07 0 01-2.34-1.55 7.45 7.45 0 01-2.16-5.31v-.05a7.49 7.49 0 012.15-5.3A7.2 7.2 0 0162 5.64a7.81 7.81 0 013.02-.58 8.65 8.65 0 012.01.22 6.87 6.87 0 011.65.61 6.6 6.6 0 011.35.96 7.86 7.86 0 011.08 1.2l-3 2.32a5.17 5.17 0 00-1.34-1.23 3.35 3.35 0 00-1.79-.45 3.17 3.17 0 00-1.38.3 3.3 3.3 0 00-1.07.81 3.78 3.78 0 00-.71 1.2 4.23 4.23 0 00-.26 1.48v.04a4.38 4.38 0 00.26 1.5 3.75 3.75 0 00.7 1.23 3.3 3.3 0 001.08.8 3.18 3.18 0 001.38.3 3.92 3.92 0 001.02-.12 3.1 3.1 0 00.84-.35 4.58 4.58 0 00.71-.56 8.36 8.36 0 00.67-.7l2.99 2.13a10.6 10.6 0 01-1.12 1.29 6.4 6.4 0 01-1.37 1.02 7.18 7.18 0 01-1.72.68 8.58 8.58 0 01-2.14.24zM72.4 5.36h3.97v10.86h6.95v3.47H72.4zM91.72 19.98a7.97 7.97 0 01-3.07-.58 7.56 7.56 0 01-2.44-1.59 7.32 7.32 0 01-1.6-2.36 7.2 7.2 0 01-.6-2.88v-.05a7.31 7.31 0 012.22-5.27 7.72 7.72 0 012.46-1.6 8.38 8.38 0 016.15 0 7.56 7.56 0 012.43 1.59 7.33 7.33 0 011.61 2.35 7.2 7.2 0 01.59 2.9v.03a7.31 7.31 0 01-2.22 5.28 7.72 7.72 0 01-2.46 1.6 7.97 7.97 0 01-3.07.58zm.04-3.58a3.58 3.58 0 001.5-.31 3.45 3.45 0 001.15-.83 3.85 3.85 0 00.74-1.22 4.08 4.08 0 00.26-1.48v-.04a4.07 4.07 0 00-.26-1.47 3.78 3.78 0 00-.76-1.23 3.74 3.74 0 00-1.17-.85 3.72 3.72 0 00-2.98-.01 3.58 3.58 0 00-1.15.83 3.62 3.62 0 00-.74 1.22 4.24 4.24 0 00-.25 1.47v.04a4.1 4.1 0 00.26 1.48 3.87 3.87 0 00.75 1.23 3.6 3.6 0 001.16.85 3.48 3.48 0 001.5.32zM101.58 5.23h4.1v2.09a6.49 6.49 0 011.82-1.69 5 5 0 012.68-.66 6.41 6.41 0 012.45.49 6.06 6.06 0 012.1 1.44 7.21 7.21 0 011.47 2.35 8.61 8.61 0 01.56 3.2v.05a8.61 8.61 0 01-.56 3.2 7.34 7.34 0 01-1.45 2.35 5.95 5.95 0 01-2.09 1.44 6.49 6.49 0 01-2.48.49 5.15 5.15 0 01-2.7-.65 7.22 7.22 0 01-1.8-1.51V24h-4.1zm7.54 11.26a3.3 3.3 0 001.37-.28 3.38 3.38 0 001.11-.81 3.91 3.91 0 00.77-1.26 4.52 4.52 0 00.29-1.64v-.06a4.54 4.54 0 00-.29-1.63 3.9 3.9 0 00-.77-1.27 3.4 3.4 0 00-1.11-.8 3.41 3.41 0 00-2.73 0 3.25 3.25 0 00-1.1.8 4.03 4.03 0 00-.76 1.27 4.54 4.54 0 00-.28 1.63v.06a4.54 4.54 0 00.28 1.63 4.02 4.02 0 00.75 1.27 3.24 3.24 0 001.11.8 3.3 3.3 0 001.36.3zM125.96 20.01a8.24 8.24 0 01-3-.54 6.96 6.96 0 01-2.4-1.53 7.1 7.1 0 01-1.58-2.36 7.83 7.83 0 01-.57-3.03v-.06a8.08 8.08 0 01.53-2.9 7.4 7.4 0 011.47-2.4 6.85 6.85 0 015.15-2.22 7.04 7.04 0 013.12.65 6.36 6.36 0 012.2 1.74 7.22 7.22 0 011.3 2.5 10.34 10.34 0 01.42 2.95l-.02.51-.04.57h-10.06a3.46 3.46 0 001.23 2.12 3.67 3.67 0 002.3.72 4.56 4.56 0 001.84-.35 6.22 6.22 0 001.67-1.13l2.35 2.07a7.27 7.27 0 01-2.48 1.98 7.7 7.7 0 01-3.43.71zm2.64-8.68a3.99 3.99 0 00-.97-2.22 2.69 2.69 0 00-2.07-.85 2.75 2.75 0 00-2.1.83 4.18 4.18 0 00-1.03 2.24zM140.9 19.97a6.42 6.42 0 01-2.45-.48 6.07 6.07 0 01-2.1-1.45 7.2 7.2 0 01-1.47-2.35 8.6 8.6 0 01-.55-3.2v-.05a8.6 8.6 0 01.55-3.2 7.33 7.33 0 011.46-2.34 5.92 5.92 0 012.09-1.44 6.48 6.48 0 012.47-.49 5.14 5.14 0 012.71.65 7.26 7.26 0 011.8 1.5V0h4.1v19.7h-4.1v-2.07a6.5 6.5 0 01-1.83 1.68 5 5 0 01-2.68.66zm1.06-3.48a3.3 3.3 0 001.36-.28 3.25 3.25 0 001.1-.81 4.03 4.03 0 00.76-1.27 4.55 4.55 0 00.29-1.63v-.05a4.54 4.54 0 00-.29-1.64 4.04 4.04 0 00-.75-1.27 3.26 3.26 0 00-1.1-.8 3.41 3.41 0 00-2.73 0 3.39 3.39 0 00-1.12.8 3.92 3.92 0 00-.77 1.26 4.52 4.52 0 00-.28 1.65v.05a4.55 4.55 0 00.28 1.63 3.89 3.89 0 00.77 1.27 3.38 3.38 0 001.12.81 3.3 3.3 0 001.36.28zM152.58 0h4.31v3.65h-4.3zm.11 5.23h4.1v14.46h-4.1zM204.8 20.01a8.19 8.19 0 01-3.1-.58 7.58 7.58 0 01-2.47-1.59 7.4 7.4 0 01-1.64-2.37 7.25 7.25 0 01-.59-2.92v-.06a7.25 7.25 0 01.6-2.92 7.46 7.46 0 011.64-2.39 7.8 7.8 0 012.48-1.62 8.09 8.09 0 013.13-.59 8.17 8.17 0 013.1.58 7.57 7.57 0 012.46 1.6 7.4 7.4 0 011.64 2.36 7.24 7.24 0 01.59 2.93v.05a7.25 7.25 0 01-.6 2.93 7.45 7.45 0 01-1.64 2.38 7.8 7.8 0 01-2.48 1.62 8.08 8.08 0 01-3.13.6zm.05-3.54a3.79 3.79 0 001.57-.3 3.46 3.46 0 001.17-.85 3.74 3.74 0 00.74-1.25 4.46 4.46 0 00.26-1.52v-.06a4.26 4.26 0 00-.27-1.52 3.82 3.82 0 00-2-2.13 3.61 3.61 0 00-1.53-.33 3.8 3.8 0 00-1.57.31 3.47 3.47 0 00-1.17.85 3.73 3.73 0 00-.74 1.25 4.47 4.47 0 00-.26 1.52v.05a4.27 4.27 0 00.27 1.52 3.86 3.86 0 001.98 2.14 3.59 3.59 0 001.55.32zM214.94 5.23h4.1v2.05a8.81 8.81 0 01.77-.87 5.32 5.32 0 01.93-.74 4.62 4.62 0 011.15-.51 4.98 4.98 0 011.41-.19 4.91 4.91 0 012.47.6 4.01 4.01 0 011.6 1.69 6.6 6.6 0 012.1-1.71 5.84 5.84 0 012.65-.58 4.74 4.74 0 013.59 1.35 5.51 5.51 0 011.3 3.96v9.41h-4.1v-8.06a3.36 3.36 0 00-.63-2.2 2.2 2.2 0 00-1.78-.74 2.31 2.31 0 00-1.82.74 3.21 3.21 0 00-.67 2.2v8.07h-4.1v-8.07a3.35 3.35 0 00-.62-2.2 2.2 2.2 0 00-1.78-.74 2.32 2.32 0 00-1.82.74 3.21 3.21 0 00-.66 2.2v8.07h-4.1zM171.12 12.8a6.45 6.45 0 011.05-3.53l-.16-.6a4.86 4.86 0 00-1.2-1.97 5.17 5.17 0 00-1.98-1.2 8.89 8.89 0 00-2.9-.42 13.07 13.07 0 00-3.13.32 16.1 16.1 0 00-2.48.84l1.03 3.12a13.94 13.94 0 011.9-.58 9.67 9.67 0 012.09-.2 3.46 3.46 0 012.32.68 2.47 2.47 0 01.78 1.97v.25a11.96 11.96 0 00-1.6-.43 10.06 10.06 0 00-1.92-.16 9.12 9.12 0 00-2.35.28 5.37 5.37 0 00-1.83.85 3.93 3.93 0 00-1.2 1.43 4.55 4.55 0 00-.43 2.05v.05a4.39 4.39 0 00.39 1.9 4.07 4.07 0 001.06 1.39 4.51 4.51 0 001.57.85 6.4 6.4 0 001.93.28 5.91 5.91 0 002.56-.5 5.68 5.68 0 001.8-1.34l-.02 1.57h3.97v-3.06a6.45 6.45 0 01-1.25-3.84zm-2.62 1.8a2.24 2.24 0 01-.87 1.83 3.6 3.6 0 01-2.32.7 2.63 2.63 0 01-1.6-.46 1.51 1.51 0 01-.63-1.29v-.05a1.68 1.68 0 01.75-1.49 3.63 3.63 0 012.07-.5 6.4 6.4 0 011.4.14 6.29 6.29 0 011.2.4zM193.66 14.94a7.57 7.57 0 01-1.53 1.11 3.7 3.7 0 01-1.79.42 3.58 3.58 0 01-1.5-.3 3.5 3.5 0 01-1.17-.85 3.7 3.7 0 01-.74-1.27 4.65 4.65 0 01-.26-1.56v-.05a4.45 4.45 0 01.26-1.52 3.84 3.84 0 01.73-1.25 3.5 3.5 0 011.1-.85 3.19 3.19 0 011.42-.3 3.63 3.63 0 011.85.42 6.72 6.72 0 011.44 1.16l2.5-2.7a7.65 7.65 0 00-2.36-1.78 7.83 7.83 0 00-3.4-.65 7.73 7.73 0 00-3.07.6 7.3 7.3 0 00-2.39 1.61 7.47 7.47 0 00-1.54 2.35 6.45 6.45 0 01.14 6.27 7.3 7.3 0 001.4 2.01 7.4 7.4 0 002.4 1.6 7.58 7.58 0 003 .6 7.24 7.24 0 003.5-.75 9.22 9.22 0 002.4-1.9z" class="a" data-webtasks-id="a3006605-3ef7-425e"></path> <path fill="#f05b13" d="M181.62 12.8a4.01 4.01 0 11-4.01-4.01 4.01 4.01 0 014.01 4z" data-webtasks-id="622e4be1-2e35-4ac9"></path> </symbol> </svg></div><div id="logo" data-webtasks-id="22e08764-8548-4b98"> <a id="imagelink" href="/" title="Home" rel="home" class="site-branding__logo" data-webtasks-id="4928fbe4-16f1-49e3"> <svg width="237" height="24" data-webtasks-id="452d1560-ccd2-410e"><use xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#encyclopedia-logo" data-webtasks-id="d4b9410b-c27d-4d22"></use></svg> </a></div></div><div class="col hdr-r justify-content-end d-flex align-items-center" data-webtasks-id="3844dfca-0331-4cb8"><div id="search-form" data-webtasks-id="c76c10f0-5aff-48ad"><form action="https://www.encyclopedia.com/gsearch" method="get" data-webtasks-id="7fba3c2a-6190-4414"><div class="js-form-item form-item js-form-type-search form-item-keys js-form-item-keys form-no-label" data-webtasks-id="17c97f7e-a38e-47b2"> <span class="field-preffix" data-webtasks-id="c134bed3-7207-486a"> <input class="button js-form-submit form-submit" data-drupal-selector="edit-submit" type="submit" id="edit-submit" value="" data-webtasks-id="b9baab01-6244-4704"> </span> <input title="Enter the terms you wish to search for." class="searchbox form-search form-input" placeholder="What do you want to learn today?" data-drupal-selector="edit-keys" type="search" id="edit-keys" name="q" value="" size="15" maxlength="128" data-webtasks-id="e74f331d-de73-4a04" spellcheck="false" data-ms-editor="true"> <span class="field-suffix" data-webtasks-id="fa8f30ea-cf40-4d23"> <i class="fa ency-close" data-webtasks-id="88cc8869-b70c-4de7"></i> </span></div><div data-drupal-selector="edit-actions" class="form-actions js-form-wrapper form-wrapper" id="edit-actions" data-webtasks-id="c9d4e29a-bfca-4832"> <input class="button js-form-submit form-submit" data-drupal-selector="edit-submit" type="submit" id="edit-submit" value="Search" data-webtasks-id="2f49e59b-1651-4fa0"></div></form></div> <span class="mobile-search-icon" data-webtasks-id="b9ff6d1c-3bb2-4e4e"><i class="fa ency-search" data-webtasks-id="fa59e4fc-f2cc-4ee0"></i></span><div class="hdr-categories-container" data-webtasks-id="3aa855d1-85cb-4f2e"><a id="rcLink" class="rc-link" onclick="if (!window.__cfRLUnblockHandlers) return false; toggleFlyout()" data-webtasks-id="769785af-485e-4cf1"><span class="text" id="block-trustme-main-menu-menu" data-webtasks-id="6c7fe1f1-f640-4dce">EXPLORE</span><i class="fa ency-down" data-webtasks-id="e7b7879f-45ae-48a5"></i></a><div class="rc-flyout" id="rcFlyout" data-webtasks-id="9606b55c-437b-4c25"><i onclick="if (!window.__cfRLUnblockHandlers) return false; closeOverlays();" class="fa fa-close" data-webtasks-id="551ffb09-812d-46e1"></i><div class="categories" data-webtasks-id="d1cc3d83-4676-4687"> <span class="title" data-webtasks-id="0a6acba7-a83e-48b8">EXPLORE</span><ul block="block-trustme-main-menu" data-webtasks-id="c7c06ca7-634c-4da7"><li data-webtasks-id="d073bdd2-9b30-4e37"> <a href="/earth-and-environment" data-drupal-link-system-path="taxonomy/term/66206" data-webtasks-id="e94eacea-aafd-4e19">Earth and Environment</a></li><li data-webtasks-id="6fb588a9-e967-41a9"> <a href="/history" data-drupal-link-system-path="taxonomy/term/66213" data-webtasks-id="deb9d6ab-ab7c-4e85">History</a></li><li data-webtasks-id="85bbe271-0c1f-4bf9"> <a href="/literature-and-arts" data-drupal-link-system-path="taxonomy/term/66208" data-webtasks-id="25e9f440-dd6e-4c3b">Literature and the Arts</a></li><li data-webtasks-id="5bc576d8-f2a9-453a"> <a href="/medicine" data-drupal-link-system-path="taxonomy/term/66205" data-webtasks-id="172dc8aa-4a24-48a6">Medicine</a></li><li data-webtasks-id="06410ae3-8dfe-4c85"> <a href="/people" data-drupal-link-system-path="taxonomy/term/66211" data-webtasks-id="ea1cb1a9-7703-472a">People</a></li><li data-webtasks-id="9451f801-27d2-4bf8"> <a href="/philosophy-and-religion" data-drupal-link-system-path="taxonomy/term/66209" data-webtasks-id="c5396e69-1e20-4a1f">Philosophy and Religion</a></li><li data-webtasks-id="4cbbd44c-a2f9-4eaf"> <a href="/places" data-drupal-link-system-path="taxonomy/term/66214" data-webtasks-id="aa6f34c6-f650-482c">Places</a></li><li data-webtasks-id="94aa2ed0-e5e6-4fbb"> <a href="/plants-and-animals" data-drupal-link-system-path="taxonomy/term/66210" data-webtasks-id="c84c5ffc-3bf5-4297">Plants and Animals</a></li><li data-webtasks-id="696d1b3d-889b-4cbf"> <a href="/science-and-technology" data-drupal-link-system-path="taxonomy/term/66204" data-webtasks-id="7a7d7798-c583-4d65">Science and Technology</a></li><li data-webtasks-id="ef540eee-d36a-4377"> <a href="/social-sciences-and-law" data-drupal-link-system-path="taxonomy/term/66207" data-webtasks-id="8befd5f0-6f7d-4d00">Social Sciences and the Law</a></li><li data-webtasks-id="d18e5ca0-2a44-4ed7"> <a href="/sports-and-everyday-life" data-drupal-link-system-path="taxonomy/term/66212" data-webtasks-id="d03f5086-2ef3-4120">Sports and Everyday Life</a></li><li data-webtasks-id="86b3a4bf-2b82-4795"> <a href="/references" data-drupal-link-system-path="references" data-webtasks-id="e9a1c119-8e4d-455f">Additional References</a></li><li data-webtasks-id="b3d82313-a5cf-4dcc"> <a href="https://www.encyclopedia.com/articles/" data-webtasks-id="ba826858-0e53-4788">Articles</a></li><li data-webtasks-id="2e3c316d-6d6a-4bed"> <a href="/daily/" title="Daily History" data-webtasks-id="11ae1779-6007-4f36">Daily</a></li></ul></div></div></div></div></div></div> </header><div class="print-logo" data-webtasks-id="505ccad4-7690-4b22"><div data-webtasks-id="94a692c6-79cc-4af7"><div id="block-trustme-printlogo" data-webtasks-id="4f64bd74-0e34-416f"><div data-webtasks-id="dd4c185d-d7cb-488d"><p data-webtasks-id="cdf9acfb-84ce-4856"><img alt="Encyclopedia.com -- Online dictionary and encyclopedia of facts, information, and biographies" src="/themes/custom/trustme/images/header-logo.jpg" data-webtasks-id="8754f8af-b452-4b8d"></p></div></div></div></div><div id="wrapper" data-webtasks-id="d2e18567-f927-4548"> <a id="main-content" tabindex="-1" data-webtasks-id="8fe29a39-368c-45da"></a><div class="dialog-off-canvas-main-canvas" data-off-canvas-main-canvas="" data-webtasks-id="357ec22f-575d-4a9e"><div class="homepage" data-webtasks-id="c9ecd30b-db79-43ae"><div style="background-image: url('/sites/default/files/images/hero/enc_hero01_3.png');" id="block-heroblock" class="ency-loaded" data-webtasks-id="5a7fbe49-8ef8-4703"><div class="ency-loaded mask-hero" data-webtasks-id="ef9899f6-1f38-4705"></div><h4 data-webtasks-id="1ea51e98-3fcd-4e30">The World’s #1 Online Encyclopedia</h4><div class="clear-both hero" data-webtasks-id="2a2f059e-3cfe-4623"><div class="ency-hero-body" data-webtasks-id="41d9737f-ee5c-479d"><p data-webtasks-id="cbc9da0e-b69d-400e">Search over 200 individual encyclopedias and reference books from the worlds most trusted publishers.</p></div><div class="list-img" data-webtasks-id="99a266a2-53b8-4d6c"> <img src="/sites/default/files/images/hero/OxfordLogo%402x_2.png" alt="" data-webtasks-id="06f51b3c-25d2-4756"> <img src="/sites/default/files/images/hero/ColumbiaLogo%402x_1.png" alt="" data-webtasks-id="cd742341-c749-4377"> <img src="/sites/default/files/images/hero/CengageLogo%402x_2.png" alt="" data-webtasks-id="6ad6c720-f1d5-4cf3"></div><div class="ency-hero-search" data-webtasks-id="4f4e3989-d5a0-4af2"><form action="https://www.encyclopedia.com/gsearch" method="get" data-webtasks-id="c7fbc11c-0949-4ab2"><div class="js-form-item form-item js-form-type-search form-item-keys js-form-item-keys form-no-label" data-webtasks-id="8d8afc84-5b97-477a"> <span class="field-preffix" data-webtasks-id="6772f9ee-abc1-47f0"> <input class="button js-form-submit form-submit" data-drupal-selector="edit-submit" type="submit" id="edit-submit" value="" data-webtasks-id="43e5c1aa-0e97-445b"> </span> <input title="" class="searchbox form-search form-input" placeholder="What do you want to learn today?" data-drupal-selector="edit-keys" type="search" id="edit-keys" name="q" value="" size="15" maxlength="128" data-webtasks-id="67e2a5fb-8b1d-41a0" spellcheck="false" data-ms-editor="true" data-event-id="2" listener="true"> <span class="field-suffix" data-webtasks-id="91d02b4c-8348-45c7"> <i class="fa ency-close" data-webtasks-id="d0bee199-9550-4267"></i> </span></div><div data-drupal-selector="edit-actions" class="form-actions js-form-wrapper form-wrapper" id="edit-actions" data-webtasks-id="c88995d3-acf8-4251"> <input class="button js-form-submit form-submit" data-drupal-selector="edit-submit" type="submit" id="edit-submit" value="Search" data-webtasks-id="fedfb512-949e-42b3"></div></form></div><div class="clear-both hero footer-copy" data-webtasks-id="702ea8e4-dbbe-403f"><p data-webtasks-id="cf2938bd-fa30-491d"><a href="/about" data-webtasks-id="bf33a062-fb67-44f0">Read more</a> about our content and why so many people love it.</p></div></div></div><div id="block-picksoftheweek" data-webtasks-id="652496a5-0f2d-4fb4"><h4 data-webtasks-id="c93edf1d-6cbf-426b">Picks of the week</h4><div class="clear-both picks-of-the-week-container container" data-webtasks-id="163f03a1-0af2-436a"><div class="pick-of-week-item" style="background-image: url('sites/default/files/10/6008046.jpg')" ;="" data-webtasks-id="6b02178a-11ec-4b88"> |
|
<div class="mask-pick" data-webtasks-id="4f4c2a3c-065e-4482"></div> |
|
<a href="/people/history/mexican-history-biographies/porfirio-diaz" hreflang="en" data-webtasks-id="ea10e8f9-a625-41cf">view</a> |
|
<span class="categories" data-webtasks-id="1bceeae9-2fb2-495e">Mexican History: Biographies</span> |
|
<h3 class="heading" data-webtasks-id="4c25d5c4-561b-438c">Porfirio Diaz</h3> |
|
<p class="item-body" data-webtasks-id="a3eda14f-5506-4506"></p> |
|
</div> |
|
<div class="pick-of-week-item" style="background-image: url('sites/default/files/0/512207.jpg')" ;="" data-webtasks-id="e5e61ea4-033e-45bc"> |
|
<div class="mask-pick" data-webtasks-id="e10aa12b-5bc6-4d16"></div> |
|
<a href="/literature-and-arts/art-and-architecture/architecture/stoa" hreflang="en" data-webtasks-id="6d02d913-962f-4019">view</a> |
|
<span class="categories" data-webtasks-id="5f98e9a8-55d9-42fd">Architecture</span> |
|
<h3 class="heading" data-webtasks-id="fa26efd8-020d-4807">stoa</h3> |
|
<p class="item-body" data-webtasks-id="604d3ced-4aed-4ff1">stoa , in ancient Greek architecture, an extended, roofed colonnade on a street or square.</p> |
|
</div></div></div><div id="block-lookwhosusingencyclopediacom" data-webtasks-id="190583a5-fadf-4d58"><h4 data-webtasks-id="7a87dc5d-10bb-43fd">Look who's using encyclopedia.com</h4><div class="clear-both who-is-it-block" data-webtasks-id="5245ad51-c2bb-4567"><div class="block-body" data-webtasks-id="44bfa2f5-c5a5-49cd"><p data-webtasks-id="44a3329b-78e3-49cc">Top universities and institutions use encyclopedia.com every day for their research.</p></div><div class="whoslooking-slider" data-webtasks-id="9802f686-d732-4f10"><div class="whoslooking-item" data-webtasks-id="563be2c2-de0b-4a68"><div data-webtasks-id="b8d3dd0d-1db9-47f0"> <img src="/sites/default/files/images/whouseit/a70c83d26434d18cd9089a26ad0064f6%20%281%29.png" alt="Pandemic Flu" data-webtasks-id="7ba4ea84-3608-430d"></div> <span data-webtasks-id="d3d73b25-f1d9-44d7">Recently researched about</span><h5 data-webtasks-id="9748d963-a9df-46b0">Pandemic Flu</h5> <a href="http://nieman.harvard.edu/wp-content/uploads/pod-assets/microsites/NiemanGuideToCoveringPandemicFlu/TheScience/SwineFluBasics.aspx.html" data-webtasks-id="d2e26058-80e7-4769">Read Here</a></div><div class="whoslooking-item" data-webtasks-id="803af907-2655-48d1"><div data-webtasks-id="ee4017f0-0736-4451"> <img src="/sites/default/files/images/whouseit/nasa2.png" alt="Bacteriophages" data-webtasks-id="b497318b-0c77-46a4"></div> <span data-webtasks-id="29b0ea65-1e03-4ee8">Recently researched about</span><h5 data-webtasks-id="0e073c76-33bd-442d">Bacteriophages</h5> <a href="https://apod.nasa.gov/apod/ap080421.html" data-webtasks-id="75094d64-5357-4f00">Read Here</a></div><div class="whoslooking-item" data-webtasks-id="ab0f83d4-a43a-463a"><div data-webtasks-id="d9cc58b6-5c11-4d16"> <img src="/sites/default/files/images/whouseit/nytimes-logo-png-new-york-times-speaks-to-dr-derevensky-regarding-internet-gambling-fantasy-sports-betting-430.png" alt="The Anglerfish" data-webtasks-id="db6505ff-605d-4736"></div> <span data-webtasks-id="bfe4186b-79fb-481e">Recently researched about</span><h5 data-webtasks-id="cbfc2d9a-60b8-4f9f">The Anglerfish</h5> <a href="https://www.nytimes.com/2019/07/29/science/anglerfish-bioluminescence-deep-sea.html" data-webtasks-id="ab47347f-8113-4395">Read Here</a></div></div></div></div><div id="block-populartopics" data-webtasks-id="0ae96d12-6e5c-43a4"><div class="popular-topics-container container" data-webtasks-id="c409d7de-1bb2-4efb"><div class="ency-topics" data-webtasks-id="9202c662-4c93-4633"> <a href="/social-sciences-and-law/economics-business-and-labor/taxation/income-tax" data-webtasks-id="f7f736a0-ac7e-4281"><div class="ency-topic-bkg" style="background-image: url('/sites/default/files/0/627218.jpg');" data-webtasks-id="7b3e9c69-c66c-4e4d"><div class="mask-popular" data-webtasks-id="db44fd2e-c85d-46d8"></div> <span class="category" data-webtasks-id="ea855de3-1c37-4045">Taxation</span><h3 data-webtasks-id="b9a383fd-ed19-4219">income tax</h3><p data-webtasks-id="35f8926f-84ed-4b80">income tax assessment levied upon individual or corporate incomes.</p></div> </a> <a href="/medicine/diseases-and-conditions/pathology/autism" data-webtasks-id="6b9aa1af-ae72-4a54"><div class="ency-topic-bkg" style="background-image: url('/sites/default/files/4/2792955.jpg');" data-webtasks-id="5dd23f29-b3fa-43c8"><div class="mask-popular" data-webtasks-id="e24efd9c-b307-4c4f"></div> <span class="category" data-webtasks-id="f13787bc-3e80-42ba">Pathology</span><h3 data-webtasks-id="bfdffd07-f3d9-48a9">autism</h3><p data-webtasks-id="34513b82-d9a5-4137">autism , developmental disability resulting from a neurological disorder that affects the normal functioning of the brain.</p></div> </a> <a href="/philosophy-and-religion/eastern-religions/buddhism/pure-land-buddhism" data-webtasks-id="42d50539-1b2c-4111"><div class="ency-topic-bkg" style="background-image: url('/sites/default/files/6/2801633.jpg');" data-webtasks-id="841571ea-f811-42d7"><div class="mask-popular" data-webtasks-id="beb1045b-c019-4ec5"></div> <span class="category" data-webtasks-id="f6121e8c-a4ac-460e">Buddhism</span><h3 data-webtasks-id="b1e50a24-7fc6-4f36">Pure Land Buddhism</h3><p data-webtasks-id="c4a59ec7-3844-46d2">Pure Land Buddhism or Amidism, devotional sect of Mahayana Buddhism in China and Japan, centering on worship of the Buddha Amitabha.</p></div> </a> <a href="/history/united-states-and-canada/us-history/boston-tea-party" data-webtasks-id="5f926deb-6f7c-47af"><div class="ency-topic-bkg" style="background-image: url('/sites/default/files/4/2793250.jpg');" data-webtasks-id="eb2be597-c4df-4b79"><div class="mask-popular" data-webtasks-id="226a9198-5166-487f"></div> <span class="category" data-webtasks-id="33be3470-5d20-4622">U.S. History</span><h3 data-webtasks-id="3c7c6d06-0960-4db3">Boston Tea Party</h3><p data-webtasks-id="290662f7-331e-428d">Boston Tea Party 1773.</p></div> </a> <a href="/people/history/explorers-travelers-and-conquerors-biographies/hernan-cortes" data-webtasks-id="a536a0e0-e677-462d"><div class="ency-topic-bkg" style="background-image: url('/sites/default/files/4/2796049.jpg');" data-webtasks-id="48c22da6-9e3d-46bf"><div class="mask-popular" data-webtasks-id="06f0954f-4b8b-4333"></div> <span class="category" data-webtasks-id="8575a278-caf5-4558">Explorers, Travelers, and Conquerors: Biographies</span><h3 data-webtasks-id="7e957f87-8509-4e65">Hernan Cortes</h3><p data-webtasks-id="dc947035-791a-4762">Hernán Cortés or Hernando Cortez , 1485-1547, Spanish conquistador , conqueror of Mexico.</p></div> </a> <a href="/places/britain-ireland-france-and-low-countries/french-and-benelux-physical-geography/pyrenees" data-webtasks-id="476bd600-65cd-4590"><div class="ency-topic-bkg" style="background-image: url('/sites/default/files/6/2801644.jpg');" data-webtasks-id="0d1fb617-9bac-47ef"><div class="mask-popular" data-webtasks-id="14a8dc53-535d-4a7e"></div> <span class="category" data-webtasks-id="3e1f296e-6f0b-41a7">French and Benelux Physical Geography</span><h3 data-webtasks-id="047cbf29-a5c3-4de3">Pyrenees</h3><p data-webtasks-id="58a644fe-5583-49bb">Pyrenees , Span. Pirineos, Fr.</p></div> </a></div><div class="ency-more-topics" data-webtasks-id="d005ea5c-4071-4715"><h3 data-webtasks-id="7a010618-2de8-435d">More topics</h3> <a href="/science-and-technology/biology-and-genetics/environmental-studies/environmentalism" data-webtasks-id="d13f8f0e-bd3a-445a">environmentalism</a> <a href="/medicine/divisions-diagnostics-and-procedures/medicine/surrogate-mother" data-webtasks-id="ae5cf93c-8927-4923">surrogate mother</a> <a href="/social-sciences-and-law/political-science-and-government/us-government/education" data-webtasks-id="04a6bf5a-7fde-433a">education</a> <a href="/sports-and-everyday-life/sports/sports/martial-arts" data-webtasks-id="fc53742a-f9ca-4b30">martial arts</a> <a href="/places/spain-portugal-italy-greece-and-balkans/spanish-and-portuguese-political-geography/barcelona" data-webtasks-id="3ff0d241-df95-49ae">Barcelona</a></div></div></div><div id="block-codieblock" data-webtasks-id="73a96693-a439-4a92"><div class="clear-both codie-block" data-webtasks-id="92b4c27d-877a-4aa1"><div class="logo-ency" data-webtasks-id="c4d94b9b-2dbd-4863"> <svg width="237" height="24" data-webtasks-id="8a1afb49-7a78-4180"><use xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#encyclopedia-logo" data-webtasks-id="03cbdaaa-2d73-48b2"></use></svg></div><div data-webtasks-id="c732a5a6-d788-4d00"><p data-webtasks-id="fc49b4be-eaaf-4226">Best Online Consumer Information Service</p><p class="highlight" data-webtasks-id="b2c093b2-c7ca-4a11">Award winner 2009 / 2010</p><p data-webtasks-id="e8bc1d47-a4c3-40ec"> </p></div></div></div><div id="block-trustme-bottomcontentad" data-webtasks-id="ac7ebf0e-2535-4d10"></div><div class="views-element-container" data-webtasks-id="894be623-c764-448a"><div class="js-view-dom-id-fa0b8601e3c8c4762b734b4b55c678ebab05463414cf6c67491351a315bc31cf" data-webtasks-id="eb31feb6-275b-4dc0"></div></div></div></div></div><div id="footer" data-webtasks-id="c9db8f90-c145-4b01"> <footer data-webtasks-id="d2b82b93-1c13-4578"><div data-webtasks-id="f30c7bae-d85d-44a5"><div class="container" data-webtasks-id="d952c33c-62f9-48b2"><div id="block-trustme-footerad" data-webtasks-id="b414c8a5-2631-4244"></div></div><div id="block-trustme-sociallinks" data-webtasks-id="effae9fc-89d4-409a"><div data-webtasks-id="ac4834ce-f4fa-4604"><nav class="social" data-webtasks-id="b8810ede-161a-41a8"><a href="https://www.facebook.com/encyclopediacom" target="_blank" title="Facebook" data-webtasks-id="33a9e5a6-d7bc-41f8"><i data-webtasks-id="28287a14-c063-494f"><svg xmlns="http://www.w3.org/2000/svg" width="25" height="25" viewBox="0 0 13.4 25" data-webtasks-id="5213b8da-8eca-44d0"><defs data-webtasks-id="690da9bc-29b7-415b"></defs></svg><br data-webtasks-id="ad5ac214-f735-4e93"><path fill="#ffffff" d="M12.5 14.1H8.85V25H3.96V14.1H-.01V9.58h3.97V6.13C3.96 2.21 6.3.04 9.87.04c1.71 0 3.5.306 3.5.306v3.85H11.4c-1.94 0-2.55 1.21-2.55 2.44v2.94h4.34z" data-webtasks-id="1a210e7b-6e3b-4977"></path></i></a><a href="https://twitter.com/encyclopediacom" target="_blank" title="Twitter" data-webtasks-id="f36fb40a-61df-4a4c"><i data-webtasks-id="b6c01c37-660f-4ccd"><svg xmlns="http://www.w3.org/2000/svg" width="25" height="25" viewBox="0 0 30.8 25" data-webtasks-id="1d390f7f-c797-47a3"><defs data-webtasks-id="b3a70ddb-2ad3-4529"></defs></svg><br data-webtasks-id="f7bea6e7-daf7-4285"><path fill="#ffffff" d="M27.6 6.23c.0196.273.0196.547.0196.82 0 8.34-6.35 17.9-17.9 17.9-3.57 0-6.89-1.04-9.69-2.83.508.0585.996.0781 1.52.0781 2.95 0 5.66-.996 7.83-2.7-2.77-.0587-5.1-1.88-5.9-4.38.391.0586.781.0976 1.19.0976.566 0 1.13-.0781 1.66-.215-2.89-.586-5.06-3.12-5.06-6.19v-.0781c.84.469 1.82.762 2.85.801-1.7-1.13-2.81-3.07-2.81-5.25 0-1.17.312-2.25.859-3.18 3.11 3.83 7.77 6.33 13 6.6-.0976-.469-.156-.957-.156-1.45 0-3.48 2.81-6.31 6.31-6.31 1.82 0 3.46.762 4.61 1.99 1.43-.273 2.79-.801 4-1.52-.469 1.46-1.46 2.7-2.77 3.48 1.27-.137 2.5-.488 3.63-.977-.859 1.25-1.93 2.36-3.16 3.26z" data-webtasks-id="28fd47ff-ced9-47ef"></path></i></a><a href="https://instagram.com/encyclopediacom" target="_blank" title="Instagram" data-webtasks-id="7618313b-10bb-4792"><i data-webtasks-id="df83cdf7-7e47-4a21"><svg xmlns="http://www.w3.org/2000/svg" width="25" height="25" viewBox="0 0 25 25" data-webtasks-id="96b1446c-888c-4c28"><defs data-webtasks-id="b177de1c-f8f9-4374"></defs></svg><br data-webtasks-id="9162e824-8200-4769"><path fill="#ffffff" d="M12.5 5.95c3.55 0 6.41 2.86 6.41 6.41s-2.86 6.41-6.41 6.41-6.41-2.86-6.41-6.41 2.86-6.41 6.41-6.41zm0 10.6c2.29 0 4.17-1.87 4.17-4.17S14.8 8.21 12.5 8.21s-4.17 1.87-4.17 4.17 1.87 4.17 4.17 4.17zm8.17-10.8c0 .831-.669 1.5-1.5 1.5s-1.5-.669-1.5-1.5c0-.826.669-1.5 1.5-1.5.826 0 1.5.669 1.5 1.5zm4.25 1.52c.117 2.06.117 8.25 0 10.3-.1 2-.558 3.78-2.02 5.24-1.46 1.47-3.24 1.92-5.24 2.02-2.06.117-8.25.117-10.3 0-2-.1-3.77-.558-5.24-2.02C.65 21.35.2 19.57.1 17.57c-.117-2.06-.117-8.25 0-10.3.1-2 .552-3.78 2.02-5.24C3.59.57 5.36.11 7.36.02c2.06-.117 8.25-.117 10.3 0 2 .1 3.78.558 5.24 2.02 1.47 1.46 1.92 3.24 2.02 5.24zm-2.67 12.5c.653-1.64.502-5.55.502-7.37s.151-5.72-.502-7.37c-.441-1.1-1.28-1.94-2.38-2.38-1.64-.647-5.55-.502-7.37-.502s-5.72-.151-7.37.502c-1.1.441-1.94 1.28-2.38 2.38-.647 1.64-.502 5.55-.502 7.37s-.151 5.72.502 7.37c.441 1.1 1.28 1.94 2.38 2.38 1.64.647 5.55.502 7.37.502s5.72.151 7.37-.502c1.1-.441 1.94-1.28 2.38-2.38z" data-webtasks-id="d05d4b7f-e0a0-4ed9"></path></i></a></nav></div></div><nav role="navigation" aria-labelledby="block-trustme-footer-menu" id="block-trustme-footer" data-webtasks-id="384877a0-84cb-4211"><h2 class="visually-hidden" id="block-trustme-footer-menu" data-webtasks-id="d0c43402-0669-4e2f">Footer menu</h2><ul block="block-trustme-footer" data-webtasks-id="c04e6e33-cb44-489d"><li data-webtasks-id="c09d4336-1695-4d73"> <a href="/" rel="nofollow" data-drupal-link-system-path="<front>" class="is-active" data-webtasks-id="b25e22e8-008d-4e24">Home</a></li><li data-webtasks-id="e0665bae-153c-48ea"> <a href="/about" rel="nofollow" data-drupal-link-system-path="node/1319859" data-webtasks-id="8c3ed2c9-e414-4949">About Us</a></li><li data-webtasks-id="fee65c4c-063c-484a"> <a href="/faq" rel="nofollow" data-drupal-link-system-path="node/1319856" data-webtasks-id="ad256c13-281e-42dd">Help</a></li><li data-webtasks-id="a551aef8-7e58-400a"> <a href="/emailus" rel="nofollow" data-drupal-link-system-path="contact/feedback" data-webtasks-id="b5ba671b-4cd2-4e3e">Site Feedback</a></li><li data-webtasks-id="0b876f43-44ac-4673"> <a href="/privacy" rel="nofollow" data-drupal-link-system-path="node/1319857" data-webtasks-id="6308be9a-9f68-41a4">Privacy & Cookie Policy</a></li><li data-webtasks-id="bbcf7d88-da4c-4e4b"> <a href="/termsofservice" rel="nofollow" data-drupal-link-system-path="node/1319858" data-webtasks-id="7c86dd36-4f7f-4ade">Terms and Conditions</a></li><li data-webtasks-id="4d36acbf-4579-487d"> <a href="https://www.encyclopedia.com/daily/" title="Daily Stories" rel="nofollow" data-webtasks-id="fca2b33e-3251-437b">Daily</a></li></ul> </nav><div id="block-trustme-copyright" data-webtasks-id="e0a1dc98-2528-47c7"><div data-webtasks-id="4fefa0f2-6b62-459d"><p data-webtasks-id="b9d5d04e-594e-46ec"><span data-webtasks-id="deff4ec3-167b-429f">© 2019 Encyclopedia.com | All rights reserved.</span></p></div></div></div> </footer></div> <i class="back-to-top" data-webtasks-id="f2c7e7c8-e129-43ff"> <svg xmlns="http://www.w3.org/2000/svg" width="60" height="60" viewBox="0 300 1792 1792" data-webtasks-id="38fdfef1-4c36-4438"><path d="M1395 1184q0 13-10 23l-50 50q-10 10-23 10t-23-10l-393-393-393 393q-10 10-23 10t-23-10l-50-50q-10-10-10-23t10-23l466-466q10-10 23-10t23 10l466 466q10 10 10 23z" data-webtasks-id="b2f90d4c-cbcc-4031"></path></svg> </i><div class="overlay" onclick="if (!window.__cfRLUnblockHandlers) return false; closeOverlays();" data-webtasks-id="bf60a8a9-55b1-47df"></div><script type="application/json" data-drupal-selector="drupal-settings-json" data-webtasks-id="73221b43-b11f-4bf7">{"path":{"baseUrl":"\/","scriptPath":null,"pathPrefix":"","currentPath":"node","currentPathIsAdmin":false,"isFront":true,"currentLanguage":"en"},"pluralDelimiter":"\u0003","suppressDeprecationErrors":true,"user":{"uid":0,"permissionsHash":"307da934b26902b030680024e1773791a2d0824c3979c033e76f93f811d7f7eb"}}</script><script src="/sites/default/files/js/js_c8LbWbHV1txem3q8oAzuadnL-HiBShaQH_WRviNqT_g.js" type="text/javascript" data-webtasks-id="f9d44eda-a577-41d0"></script><script src="/sites/default/files/js/js_zqxY3WQzYNR0NiKCpM5itT0--wb4EaKcun2onM0X1is.js" type="text/javascript" data-webtasks-id="440641e4-ea90-48e4"></script><script src="/sites/default/files/js/js_7riCSsmZKOyjnTzzQILMa9_W2mWycOMuqO6ECCFCXEk.js" type="text/javascript" data-webtasks-id="1ad322c3-e7a7-4b66"></script><script src="/sites/default/files/js/js_yLV6HYxC2Rnf9ZekS8oWsZmUNhr7FkzcQDF4zydcT90.js" type="text/javascript" data-webtasks-id="9f242d94-e113-47cc"></script><script src="/sites/default/files/js/js_WGXfBW_MzOchPG9FUX5M7UvHZXqRJrIQ3Tfnf5S1iHg.js" type="text/javascript" data-webtasks-id="67097cbd-571d-44a9"></script><script src="/sites/default/files/js/js_zUQZP_05aEQQEOMOyF3c6jn8AsMhZPB5lR08eWRX8vY.js" type="text/javascript" data-webtasks-id="dcab8422-20da-4b9e"></script><iframe height="1" frameborder="0" src="https://ads.rubiconproject.com/prebid/load-cookie.html?endpoint=rubicon&max_sync_count=12&source=amp&args=account:9262" style="display: none;" data-webtasks-id="2f0c69a6-2d03-4205"></iframe><iframe src="https://ads.adthrive.com/builds/core/e1eb55f/html/topics.html" id="adthrive-topics-api" data-webtasks-id="60ed5fd0-5351-467c" style="display: none;"></iframe><iframe src="https://ads.adthrive.com/builds/core/e1eb55f/html/rnf.html" id="adthrive-mcmp" data-webtasks-id="734b490b-15b3-4e63" style="display: none;"></iframe><iframe id="__uspapiLocator" name="__uspapiLocator" data-webtasks-id="843301b9-e3d0-43fb" style="display: none;"></iframe><div id="AdThrive_Footer_1_desktop" class="adthrive-ad adthrive-footer adthrive-footer-1 adthrive-ad-cls adthrive-sticky" data-webtasks-id="b31aab0e-ab1f-4ac2" style="min-height: 90px;" data-google-query-id="CInh5vmk_P8CFZMK1Qodp-sDTw" closable="true"><div id="google_ads_iframe_/18190176,21678768125/AdThrive_Footer_1/5dc336ff22eddf534ab4417c_0__container__" style="border: 0pt none;" data-webtasks-id="fc989ffb-18ff-4298"><iframe id="google_ads_iframe_/18190176,21678768125/AdThrive_Footer_1/5dc336ff22eddf534ab4417c_0" name="google_ads_iframe_/18190176,21678768125/AdThrive_Footer_1/5dc336ff22eddf534ab4417c_0" title="3rd party ad content" width="970" height="90" scrolling="no" marginwidth="0" marginheight="0" frameborder="0" role="region" aria-label="Advertisement" tabindex="0" style="border: 0px; vertical-align: bottom;" data-google-container-id="1" data-webtasks-id="77fbab28-c71c-4a8b" data-load-complete="true"></iframe></div><span class="adthrive-close" data-webtasks-id="0ffc6f0e-808a-4c2a">×</span></div><div class="adthrive-comscore adthrive-footer-message" data-webtasks-id="07739191-8302-43fb"><span data-webtasks-id="fb6f6b2f-f0e6-41ce">A Raptive Partner Site</span></div><script type="text/javascript" async="true" src="https://cdn.brandmetrics.com/scripts/bundle/65568.js?sid=f9816ecc-b51b-4747-bc3e-1ea86a0677a2&toploc=www.encyclopedia.com" data-webtasks-id="4063aece-c672-429f"></script><iframe src="https://660a9872f3cd2c3e945046e528873b94.safeframe.googlesyndication.com/safeframe/1-0-40/html/container.html" data-webtasks-id="060ee2a9-bf47-4850" style="visibility: hidden; display: none;"></iframe><div id="confiant_tag_holder" style="display:none" data-webtasks-id="3c30ba0b-c1d3-406b"></div><iframe src="https://s.amazon-adsystem.com/iu3?cm3ppd=1&d=dtb-pub&csif=t&dl=pm-db5" style="display: none;" data-webtasks-id="fce71d87-8137-40e0"></iframe><iframe src="https://www.google.com/recaptcha/api2/aframe" width="0" height="0" style="display: none;" data-webtasks-id="762ba0a6-09e2-428a"></iframe><iframe height="0" width="0" frameborder="0" src="https://feed.pghub.io/tag?us_privacy=1---&referrer_url=&page_url=https%3A%2F%2Fwww.encyclopedia.com%2F&owner=P%26G&bp_id=cafemedia&ch=%7B%22architecture%22%3A%22x86%22%2C%22bitness%22%3A%2264%22%2C%22brands%22%3A%5B%7B%22brand%22%3A%22Not.A%2FBrand%22%2C%22version%22%3A%228%22%7D%2C%7B%22brand%22%3A%22Chromium%22%2C%22version%22%3A%22114%22%7D%2C%7B%22brand%22%3A%22Google%20Chrome%22%2C%22version%22%3A%22114%22%7D%5D%2C%22fullVersionList%22%3A%5B%7B%22brand%22%3A%22Not.A%2FBrand%22%2C%22version%22%3A%228.0.0.0%22%7D%2C%7B%22brand%22%3A%22Chromium%22%2C%22version%22%3A%22114.0.5735.199%22%7D%2C%7B%22brand%22%3A%22Google%20Chrome%22%2C%22version%22%3A%22114.0.5735.199%22%7D%5D%2C%22mobile%22%3Afalse%2C%22model%22%3A%22%22%2C%22platform%22%3A%22Windows%22%2C%22platformVersion%22%3A%2215.0.0%22%7D&initiator=js" style="display: none;" data-webtasks-id="19c4d1e6-2cfd-4012"></iframe><script type="text/javascript" src="https://pghub.io/js/pandg-sdk.js" data-webtasks-id="b9188e0f-dae0-4e90"></script><iframe name="__launchpadLocator" data-webtasks-id="c437a369-f91e-4d4d" style="display: none;"></iframe></body><editor-card style="position:absolute;top:0px;left:0px;z-index:auto;display: block !important" data-webtasks-id="a158cdcd-b156-4714"><div dir="ltr" style="all: initial;" data-webtasks-id="793f52a6-b783-4de0"><div style="color: initial; font: initial; font-palette: initial; font-synthesis: initial; forced-color-adjust: initial; text-orientation: initial; text-rendering: initial; -webkit-font-smoothing: initial; -webkit-locale: initial; -webkit-text-orientation: initial; -webkit-writing-mode: initial; writing-mode: initial; zoom: initial; accent-color: initial; place-content: initial; place-items: initial; place-self: initial; alignment-baseline: initial; animation-composition: initial; animation: initial; app-region: initial; appearance: initial; aspect-ratio: initial; backdrop-filter: initial; backface-visibility: initial; background: initial; background-blend-mode: initial; baseline-shift: initial; baseline-source: initial; block-size: initial; border-block: initial; border: initial; border-radius: initial; border-collapse: initial; border-end-end-radius: initial; border-end-start-radius: initial; border-inline: initial; border-start-end-radius: initial; border-start-start-radius: initial; inset: initial; box-shadow: initial; box-sizing: initial; break-after: initial; break-before: initial; break-inside: initial; buffered-rendering: initial; caption-side: initial; caret-color: initial; clear: initial; clip: initial; clip-path: initial; clip-rule: initial; color-interpolation: initial; color-interpolation-filters: initial; color-rendering: initial; color-scheme: initial; columns: initial; column-fill: initial; gap: initial; column-rule: initial; column-span: initial; contain: initial; contain-intrinsic-block-size: initial; contain-intrinsic-size: initial; contain-intrinsic-inline-size: initial; container: initial; content: initial; content-visibility: initial; counter-increment: initial; counter-reset: initial; counter-set: initial; cursor: initial; cx: initial; cy: initial; d: initial; display: initial; dominant-baseline: initial; empty-cells: initial; fill: initial; fill-opacity: initial; fill-rule: initial; filter: initial; flex: initial; flex-flow: initial; float: initial; flood-color: initial; flood-opacity: initial; grid: initial; grid-area: initial; height: initial; hyphenate-character: initial; hyphenate-limit-chars: initial; hyphens: initial; image-orientation: initial; image-rendering: initial; initial-letter: initial; inline-size: initial; inset-block: initial; inset-inline: initial; isolation: initial; letter-spacing: initial; lighting-color: initial; line-break: initial; list-style: initial; margin-block: initial; margin: initial; margin-inline: initial; marker: initial; mask: initial; mask-type: initial; math-depth: initial; math-shift: initial; math-style: initial; max-block-size: initial; max-height: initial; max-inline-size: initial; max-width: initial; min-block-size: initial; min-height: initial; min-inline-size: initial; min-width: initial; mix-blend-mode: initial; object-fit: initial; object-position: initial; object-view-box: initial; offset: initial; opacity: initial; order: initial; orphans: initial; outline: initial; outline-offset: initial; overflow-anchor: initial; overflow-clip-margin: initial; overflow-wrap: initial; overflow: initial; overscroll-behavior-block: initial; overscroll-behavior-inline: initial; overscroll-behavior: initial; padding-block: initial; padding: initial; padding-inline: initial; page: initial; page-orientation: initial; paint-order: initial; perspective: initial; perspective-origin: initial; pointer-events: initial; position: absolute; quotes: initial; r: initial; resize: initial; rotate: initial; ruby-position: initial; rx: initial; ry: initial; scale: initial; scroll-behavior: initial; scroll-margin-block: initial; scroll-margin: initial; scroll-margin-inline: initial; scroll-padding-block: initial; scroll-padding: initial; scroll-padding-inline: initial; scroll-snap-align: initial; scroll-snap-stop: initial; scroll-snap-type: initial; scrollbar-gutter: initial; shape-image-threshold: initial; shape-margin: initial; shape-outside: initial; shape-rendering: initial; size: initial; speak: initial; stop-color: initial; stop-opacity: initial; stroke: initial; stroke-dasharray: initial; stroke-dashoffset: initial; stroke-linecap: initial; stroke-linejoin: initial; stroke-miterlimit: initial; stroke-opacity: initial; stroke-width: initial; tab-size: initial; table-layout: initial; text-align: initial; text-align-last: initial; text-anchor: initial; text-combine-upright: initial; text-decoration: initial; text-decoration-skip-ink: initial; text-emphasis: initial; text-emphasis-position: initial; text-indent: initial; text-overflow: initial; text-shadow: initial; text-size-adjust: initial; text-transform: initial; text-underline-offset: initial; text-underline-position: initial; white-space: initial; touch-action: initial; transform: initial; transform-box: initial; transform-origin: initial; transform-style: initial; transition: initial; translate: initial; user-select: initial; vector-effect: initial; vertical-align: initial; view-transition-name: initial; visibility: initial; border-spacing: initial; -webkit-box-align: initial; -webkit-box-decoration-break: initial; -webkit-box-direction: initial; -webkit-box-flex: initial; -webkit-box-ordinal-group: initial; -webkit-box-orient: initial; -webkit-box-pack: initial; -webkit-box-reflect: initial; -webkit-highlight: initial; -webkit-line-break: initial; -webkit-line-clamp: initial; -webkit-mask-box-image: initial; -webkit-mask: initial; -webkit-mask-composite: initial; -webkit-print-color-adjust: initial; -webkit-rtl-ordering: initial; -webkit-ruby-position: initial; -webkit-tap-highlight-color: initial; -webkit-text-combine: initial; -webkit-text-decorations-in-effect: initial; -webkit-text-fill-color: initial; -webkit-text-security: initial; -webkit-text-stroke: initial; -webkit-user-drag: initial; -webkit-user-modify: initial; widows: initial; width: initial; will-change: initial; word-break: initial; word-spacing: initial; x: initial; y: initial; z-index: 2147483647;" data-webtasks-id="6a41d03c-b3fc-4315"><link rel="stylesheet" href="chrome-extension://gpaiobkfhnonedkhhfjpmhdalgeoebfa/fonts/fabric-icons.css" data-webtasks-id="6a33d1ea-32a2-4d50"><div style="all: initial;" data-webtasks-id="dd5a5818-6681-4ea9"></div></div><div style="color: initial; font: initial; font-palette: initial; font-synthesis: initial; forced-color-adjust: initial; text-orientation: initial; text-rendering: initial; -webkit-font-smoothing: initial; -webkit-locale: initial; -webkit-text-orientation: initial; -webkit-writing-mode: initial; writing-mode: initial; zoom: initial; accent-color: initial; place-content: initial; place-items: initial; place-self: initial; alignment-baseline: initial; animation-composition: initial; animation: initial; app-region: initial; appearance: initial; aspect-ratio: initial; backdrop-filter: initial; backface-visibility: initial; background: initial; background-blend-mode: initial; baseline-shift: initial; baseline-source: initial; block-size: initial; border-block: initial; border: initial; border-radius: initial; border-collapse: initial; border-end-end-radius: initial; border-end-start-radius: initial; border-inline: initial; border-start-end-radius: initial; border-start-start-radius: initial; inset: initial; box-shadow: initial; box-sizing: initial; break-after: initial; break-before: initial; break-inside: initial; buffered-rendering: initial; caption-side: initial; caret-color: initial; clear: initial; clip: initial; clip-path: initial; clip-rule: initial; color-interpolation: initial; color-interpolation-filters: initial; color-rendering: initial; color-scheme: initial; columns: initial; column-fill: initial; gap: initial; column-rule: initial; column-span: initial; contain: initial; contain-intrinsic-block-size: initial; contain-intrinsic-size: initial; contain-intrinsic-inline-size: initial; container: initial; content: initial; content-visibility: initial; counter-increment: initial; counter-reset: initial; counter-set: initial; cursor: initial; cx: initial; cy: initial; d: initial; display: initial; dominant-baseline: initial; empty-cells: initial; fill: initial; fill-opacity: initial; fill-rule: initial; filter: initial; flex: initial; flex-flow: initial; float: initial; flood-color: initial; flood-opacity: initial; grid: initial; grid-area: initial; height: initial; hyphenate-character: initial; hyphenate-limit-chars: initial; hyphens: initial; image-orientation: initial; image-rendering: initial; initial-letter: initial; inline-size: initial; inset-block: initial; inset-inline: initial; isolation: initial; letter-spacing: initial; lighting-color: initial; line-break: initial; list-style: initial; margin-block: initial; margin: initial; margin-inline: initial; marker: initial; mask: initial; mask-type: initial; math-depth: initial; math-shift: initial; math-style: initial; max-block-size: initial; max-height: initial; max-inline-size: initial; max-width: initial; min-block-size: initial; min-height: initial; min-inline-size: initial; min-width: initial; mix-blend-mode: initial; object-fit: initial; object-position: initial; object-view-box: initial; offset: initial; opacity: initial; order: initial; orphans: initial; outline: initial; outline-offset: initial; overflow-anchor: initial; overflow-clip-margin: initial; overflow-wrap: initial; overflow: initial; overscroll-behavior-block: initial; overscroll-behavior-inline: initial; overscroll-behavior: initial; padding-block: initial; padding: initial; padding-inline: initial; page: initial; page-orientation: initial; paint-order: initial; perspective: initial; perspective-origin: initial; pointer-events: initial; position: absolute; quotes: initial; r: initial; resize: initial; rotate: initial; ruby-position: initial; rx: initial; ry: initial; scale: initial; scroll-behavior: initial; scroll-margin-block: initial; scroll-margin: initial; scroll-margin-inline: initial; scroll-padding-block: initial; scroll-padding: initial; scroll-padding-inline: initial; scroll-snap-align: initial; scroll-snap-stop: initial; scroll-snap-type: initial; scrollbar-gutter: initial; shape-image-threshold: initial; shape-margin: initial; shape-outside: initial; shape-rendering: initial; size: initial; speak: initial; stop-color: initial; stop-opacity: initial; stroke: initial; stroke-dasharray: initial; stroke-dashoffset: initial; stroke-linecap: initial; stroke-linejoin: initial; stroke-miterlimit: initial; stroke-opacity: initial; stroke-width: initial; tab-size: initial; table-layout: initial; text-align: initial; text-align-last: initial; text-anchor: initial; text-combine-upright: initial; text-decoration: initial; text-decoration-skip-ink: initial; text-emphasis: initial; text-emphasis-position: initial; text-indent: initial; text-overflow: initial; text-shadow: initial; text-size-adjust: initial; text-transform: initial; text-underline-offset: initial; text-underline-position: initial; white-space: initial; touch-action: initial; transform: initial; transform-box: initial; transform-origin: initial; transform-style: initial; transition: initial; translate: initial; user-select: initial; vector-effect: initial; vertical-align: initial; view-transition-name: initial; visibility: initial; border-spacing: initial; -webkit-box-align: initial; -webkit-box-decoration-break: initial; -webkit-box-direction: initial; -webkit-box-flex: initial; -webkit-box-ordinal-group: initial; -webkit-box-orient: initial; -webkit-box-pack: initial; -webkit-box-reflect: initial; -webkit-highlight: initial; -webkit-line-break: initial; -webkit-line-clamp: initial; -webkit-mask-box-image: initial; -webkit-mask: initial; -webkit-mask-composite: initial; -webkit-print-color-adjust: initial; -webkit-rtl-ordering: initial; -webkit-ruby-position: initial; -webkit-tap-highlight-color: initial; -webkit-text-combine: initial; -webkit-text-decorations-in-effect: initial; -webkit-text-fill-color: initial; -webkit-text-security: initial; -webkit-text-stroke: initial; -webkit-user-drag: initial; -webkit-user-modify: initial; widows: initial; width: initial; will-change: initial; word-break: initial; word-spacing: initial; x: initial; y: initial; z-index: 2147483647;" data-webtasks-id="644d5dc9-82b0-4dab"><link rel="stylesheet" href="chrome-extension://gpaiobkfhnonedkhhfjpmhdalgeoebfa/fonts/fabric-icons.css" data-webtasks-id="dfbb929d-bb82-4820"></div></div></editor-card><iframe sandbox="allow-scripts allow-same-origin" id="67da4f7de4ce35f" frameborder="0" allowtransparency="true" marginheight="0" marginwidth="0" width="0" hspace="0" vspace="0" height="0" style="height:0px;width:0px;display:none;" scrolling="no" src="https://ads.pubmatic.com/AdServer/js/user_sync.html?gdpr=&gdpr_consent=&us_privacy=1---&gpp=&gpp_sid=&predirect=https%3A%2F%2Fprebid-server.rubiconproject.com%2Fsetuid%3Fbidder%3Dgroupm%26gdpr%3D%26gdpr_consent%3D%26us_privacy%3D1---%26gpp%3D%26gpp_sid%3D%26account%3D%26f%3Db%26uid%3D" data-webtasks-id="12d8b7c9-a56e-4c52"> |
|
</iframe><iframe sandbox="allow-scripts allow-same-origin" id="6805860651f2ef3" frameborder="0" allowtransparency="true" marginheight="0" marginwidth="0" width="0" hspace="0" vspace="0" height="0" style="height:0px;width:0px;display:none;" scrolling="no" src="https://s.adtelligent.com/sync.html?aid=817192" data-webtasks-id="931c25b9-14f2-4fc0"> |
|
</iframe> |
