What does meta http-equiv X-UA-Compatible content IE edge do

Question

What s the difference if one web page starts with   lt  DOCTYPE html gt    lt html gt      lt head gt        lt meta http-equiv  X-UA-Compatible  content  IE edge  gt     and If page starts with   lt  DOCTYPE html gt    lt html gt      lt head gt         lt  -- without X-UA-Compatible meta -- gt    If there is no difference  I suppose I can just ignore the X-UA-Compatible meta header  since I just want it to be rendered in most standard mode in all IE versions

User · Accepted Answer

October 2015 Update  This answer was posted several years ago and now the question really should be should you even consider using the X-UA-Compatible tag on your site  with the changes Microsoft has made to its browsers  more on those below    Depending upon what Microsoft browsers you support you may not need to continue using the X-UA-Compatible tag  If you need to support IE9 or IE8  then I would recommend using the tag  If you only support the latest browsers  IE11 and or Edge  then I would consider dropping this tag altogether  If you use Twitter Bootstrap and need to eliminate validation warnings  this tag must appear in its specified order  Additional info below     The X-UA-Compatible meta tag allows web authors to choose what version of Internet Explorer the page should be rendered as  IE11 has made changes to these modes  see the IE11 note below  Microsoft Edge  the browser that replaced IE11  only honors the X-UA-Compatible meta tag in certain circumstances  See the Microsoft Edge note below   According to Microsoft  when using the X-UA-Compatible tag  it should be as high as possible in your document head      If you are using the X-UA-Compatible META tag you want to place it as close to the top of the page s HEAD as possible  Internet Explorer begins interpreting markup using the latest version  When Internet Explorer encounters the X-UA-Compatible META tag it starts over using the designated version s engine  This is a performance hit because the browser must stop and restart analyzing the content    Here are your options      IE edge   IE 11   IE EmulateIE11   IE 10   IE EmulateIE10   IE 9   IE EmulateIE9  IE 8   IE EmulateIE8   IE 7   IE EmulateIE7   IE 5    To attempt to understand what each means  here are definitions provided by Microsoft      Internet Explorer supports a number of document compatibility modes that enable different features and can affect the way content is displayed           Edge mode tells Internet Explorer to display content in the highest mode available  With Internet Explorer 9  this is equivalent to IE9 mode  If a future release of Internet Explorer supported a higher compatibility mode  pages set to edge mode would appear in the highest mode supported by that version  Those same pages would still appear in IE9 mode when viewed with Internet Explorer 9    Internet Explorer supports a number of document compatibility modes that enable different features and can affect the way content is displayed     IE11 mode provides the highest support available for established and emerging industry standards  including the HTML5  CSS3 and others    IE10 mode provides the highest support available for established and emerging industry standards  including the HTML5  CSS3 and others    IE9 mode provides the highest support available for established and emerging industry standards  including the HTML5  Working Draft   W3C Cascading Style Sheets Level 3 Specification  Working Draft   Scalable Vector Graphics  SVG  1 0 Specification  and others   Editor Note  IE 9 does not support CSS3 animations     IE8 mode supports many established standards  including the W3C Cascading Style Sheets Level 2 1 Specification and the W3C Selectors API  it also provides limited support for the W3C Cascading Style Sheets Level 3 Specification  Working Draft  and other emerging standards    IE7 mode renders content as if it were displayed in standards mode by Internet Explorer 7  whether or not the page contains a  directive    Emulate IE9 mode tells Internet Explorer to use the  directive to determine how to render content  Standards mode directives are displayed in IE9 mode and quirks mode directives are displayed in IE5 mode  Unlike IE9 mode  Emulate IE9 mode respects the  directive    Emulate IE8 mode tells Internet Explorer to use the  directive to determine how to render content  Standards mode directives are displayed in IE8 mode and quirks mode directives are displayed in IE5 mode  Unlike IE8 mode  Emulate IE8 mode respects the  directive    Emulate IE7 mode tells Internet Explorer to use the  directive to determine how to render content  Standards mode directives are displayed in Internet Explorer 7 standards mode and quirks mode directives are displayed in IE5 mode  Unlike IE7 mode  Emulate IE7 mode respects the  directive  For many web sites  this is the preferred compatibility mode    IE5 mode renders content as if it were displayed in quirks mode by Internet Explorer 7  which is very similar to the way content was displayed in Microsoft Internet Explorer 5       IE10 NOTE  As of IE10  quirks mode behaves differently than it did in earlier versions of the browser  In IE9 and earlier versions  quirks mode restricted the webpage to the features supported by IE5 5  In IE10  quirks mode conforms to the differences specified in the HTML5 specification   Personally  I always choose the http-equiv  X-UA-Compatible  content  IE edge  meta tag  as older versions have plenty of bugs  and I do not want IE to decide to go into  Compatibility mode  and show my site as IE7 vs IE8 or 9  I always prefer the latest version of IE    IE11  From Microsoft       Starting with IE11  edge mode is the preferred document mode  it represents the highest support for modern standards available to the browser       Use the HTML5 document type declaration to enable edge mode        lt  doctype html gt       Edge mode was introduced in Internet Explorer 8 and has been available in each subsequent release  Note that the features supported by edge mode are limited to those supported by the specific version of the browser rendering the content       Starting with IE11  document modes are deprecated and should no longer be used  except on a temporary basis  Make sure to update sites that rely on legacy features and document modes to reflect modern standards       If you must target a specific document mode so that your site functions while you rework it to support modern standards and features  be aware that you re using a transitional feature  one that may not be available in future versions       If you currently use the x-ua-compatible header to target a legacy document mode  it s possible your site won t reflect the best experience available with IE11    Microsoft Edge  Replacement for Internet Explorer that comes bundled with Windows 10   Information on X-UA-Compatible meta tag for the  Edge  version of IE  From Microsoft       Introducing the    living    Edge document mode      As we announced in August 2013  we are deprecating document modes as of IE11  With our latest platform updates  the need for legacy document modes is primarily limited to Enterprise legacy web apps  With new architectural changes  these legacy document modes will be isolated from changes in the    living    Edge mode  which will help to guarantee a much higher level of compatibility for customers who depend on those modes and help us move even faster on improvements in Edge  IE will still honor document modes served by intranet sites  sites on the Compatibility View list  and when used with Enterprise Mode only       Public Internet sites will be rendered with the new Edge mode platform  ignoring X-UA-Compatible   It is our goal that Edge is the  living  document mode from here out and no further document modes will be introduced going forward    With the changes in Microsoft Edge to no longer support document modes in most cases  Microsoft has a tool to scan your site to check and see if it has code that is not compatible with Edge   Chrome 1 Info for IE  There is also chrome 1 that you can use or use together with one of the above options like   lt meta http-equiv  X-UA-Compatible  content  IE Edge chrome 1  gt   chrome 1 is for Google s Chrome Frame which is defined as       Google Chrome Frame is an open source browser plug-in  Users who have the plug-in installed have access to Google Chrome s open web technologies and speedy JavaScript engine when they open pages in the browser       Google Chrome Frame seamlessly enhances your browsing experience in Internet Explorer  It displays Google Chrome Frame enabled sites using Google Chrome   s rendering technology  giving you access to the latest HTML5 features as well as Google Chrome   s performance and security features without in any way interrupting your usual browser usage       When Google Chrome Frame is installed  the web just gets better without you having to think about it    But for that plug-in to work you must use chrome 1 in the X-UA-Compatible meta tag    More info on Chrome Frame can be found here   Note  Google Chrome Frame only works for IE6 through IE9  and was retired on February 25  2014  More info can be found here  Thanks to  mck for the link    Validation   HTML5    The page will validate using the W3 Validator only when using  lt meta http-equiv  X-UA-Compatible  content  IE Edge  gt   For other values it will throw the error  A meta element with an http-equiv attribute whose value is X-UA-Compatible must have a content attribute with the value IE edge  In other words  if you have IE edge chrome 1 it will not validate  I ignore this error completely as modern browsers simply ignore this line of code   If you must have completely valid code then consider doing this on the server level by setting HTTP header  As a note  Microsoft says  If both of these instructions are sent  meta and HTTP   the developer s preference  meta element  takes precedence over the web server setting  HTTP header    See olibre s answer or bitinn s answer for more details on how to set an HTTP header   XHTML  There isn t an issue with validation when using  lt meta http-equiv  X-UA-Compatible  content  IE Edge    gt  as long as the tag is properly closed  i e    gt  vs  gt     Twitter Bootstrap  This tag has been strongly recommended by the Bootstrap team since at least 2014  and Bootlint  the linter authored by the twbs team continues to throw a warning when the tag is omitted  The linter distinguishes between warnings and errors  and as such the severity of omitting this tag may be considered minor     For more information on X-UA-Compatible see Microsoft s Website Defining Document Compatibility   For more information on what IE supports see caniuse com   For more information on Twitter Bootstrap requirements  see the bootlint project wiki page

User · Answer

lt meta http-equiv  X-UA-Compatible  content  IE Edge  gt    To make this line work as expected  make sure that    It is the first element right after  lt head gt  No conditional comments are used before the meta tag  e  g  on the  lt html gt  element   Otherwise some IE versions simply ignore it   UPDATE  These two rules are simplified but they are easy to remember and to verify  Despite MSDN docs stating you can put title and other meta tags before this one  I would not recommend to do so   How make it work with conditional comments   Interesting article about the order of elements in the head   blogs msdn com  for IE   REFERENCE  From the MSDN documentation      The X-UA-Compatible       must appear in the header of the webpage  the HEAD section    before all other elements except for the title element and other meta elements

User · Answer

This is LITERALLY 1 google query away  but here goes   http   msdn microsoft com en-us library jj676915 v vs 85  aspx     Understanding legacy document modes      Use the following value to display the webpage in edge mode  which is   the highest standards mode supported by Internet Explorer  from   Internet Explorer 6 through IE11    lt meta http-equiv  x-ua-compatible  content  IE edge        Note that this is functionally equivalent to using the HTML5 doctype  It places Internet Explorer into the highest supported   document mode  Edge most is most useful for regularly maintained   websites that are routinely tested for interoperability between   multiple browsers  including Internet Explorer       Note        Starting with IE11  edge mode is considered the preferred document mode   In earlier versions  it was considered experimental     To learn more  see Document modes are deprecated  Starting with   Windows Internet Explorer 8  some web developers used the edge mode   meta element to hide the Compatibility View button on the address bar    As of IE11  this is no longer necessary as the button has been removed   from the address bar  Because it forces all pages to be opened in   standards mode  regardless of the version of Internet Explorer  you   might be tempted to use edge mode for all pages viewed with Internet   Explorer  Don t do this  as the X-UA-Compatible header is only   supported starting with Internet Explorer 8       Tip   If you want all supported versions of Internet Explorer to open your pages in standards mode  use the HTML5 document type declaration  as shown in the earlier example    Also among the search results is    What does  lt meta http-equiv  quot X-UA-Compatible quot  content  quot IE edge quot  gt  do

User · Answer

Since I can not add a comment to the marked answer I will just post this here   In addition to the correct answer you can indeed have this validated  Since this meta tag is only directed for IE all you need to do is add a IE conditional    lt  -- if IE  gt       lt meta http-equiv  X-UA-Compatible  content  IE Edge chrome 1  gt   lt   endif -- gt    Doing this is just like adding any other IE conditional statement and only works for IE and no other browsers will be affected

User · Answer

if you use your website in the same network as the server IE likes to switch to compability mode despite DOCTYPE  Adding meta http-equiv  X-UA-Compatible  content  IE Edge  disables this unwanted behaviour

User · Answer

2 1 3 5 X-UA-Compatibility Meta Tag and HTTP Response Header  This functionality will not be implemented in any version of Microsoft Edge    lt meta http-equiv  X-UA-Compatible  content  IE 9  IE 8  IE 7  IE EDGE    gt    See https   msdn microsoft com en-us library ff955275 v vs 85  aspx  Yes  I know that I m late to the party  but I just had some issues and discussions  and in the end my boss had me remove the X-UA-Compatible tag remove from all documents I ve been working on   If this information is out-of-date or no longer relevant  please correct me

User · Answer

Just one sentence to say Instruct Internet Explorer to use its latest rendering engine   lt meta http-equiv  x-ua-compatible  content  ie edge  gt

User · Answer

The difference is that if you only specify the DOCTYPE  IE   s Compatibility View Settings take precedence  By default these settings force all intranet sites into Compatibility View regardless of DOCTYPE  There   s also a checkbox to use Compatibility View for all websites  regardless of DOCTYPE     X-UA-Compatible overrides the Compatibility View Settings  so the page will render in standards mode regardless of the browser settings  This forces standards mode for    intranet pages external web pages when the computer administrator has chosen    Display all websites in Compatibility View    as the default   think big companies  governments  universities when you unintentionally end up on the Microsoft Compatibility View List cases where users have manually added your website to the list in Compatibility View Settings   DOCTYPE alone cannot do that  you will end up in one of the Compatibility View modes in these cases regardless of DOCTYPE   If both the meta tag and the HTTP header are specified  the meta tag takes precedence    This answer is based on examining the complete rules for deciding document mode in IE8  IE9  and IE10  Note that looking at the DOCTYPE is the very last fallback for deciding the document mode

User · Answer

I think this diagram from Microsoft explains all  In order to tell IE how to render the content   DOCTYPE has to work with X-UA-Compatible meta tag   DOCTYPE by itself has no affect on changing IE Document Mode     http   ie microsoft com testdrive ieblog 2010 Mar 02 HowIE8DeterminesDocumentMode 3 png

User · Answer

Use content  IE edge chrome 1   emsp  Skip other X-UA-Compatible modes   lt meta http-equiv  X-UA-Compatible  content  IE edge chrome 1  gt                                     --------------------------     No compatibility icon The IE9 Address bar does not show up the Compatibility View button  and the page does not also show up a jumble of out-of-place menus  images  and text boxes   Features  This meta tag is required to enable javascript  JSON parse   on IE8  even when  lt  DOCTYPE html gt  is present  Correctness  Rendering Execution of modern HTML CSS JavaScript is more valid  nicer   Performance  The Trident rendering engine should run faster in its edge mode      Usage  In your HTML   lt  DOCTYPE html gt    lt html gt      lt head gt       lt meta http-equiv  X-UA-Compatible  content  IE edge chrome 1  gt     IE edge means IE should use the latest  edge  version of its rendering engine chrome 1 means IE should use the Chrome rendering engine if installed   Or better in the configuration of your web server   see also the RiaD s answer    Apache as proposed by pixeline   lt IfModule mod setenvif c gt     lt IfModule mod headers c gt      BrowserMatch MSIE ie     Header set X-UA-Compatible  IE Edge chrome 1  env ie    lt  IfModule gt   lt  IfModule gt   lt IfModule mod headers c gt    Header append Vary User-Agent  lt  IfModule gt   Nginx as proposed by Stef Pause  server            add header X-UA-Compatible  IE Edge chrome 1      Varnish proxy as proposed by Lucas Riutzel  sub vcl deliver     if  resp http Content-Type    text html          set resp http X-UA-Compatible    IE edge chrome 1          IIS  since v7    lt configuration gt     lt system webServer gt        lt httpProtocol gt           lt customHeaders gt              lt add name  X-UA-Compatible  value  IE edge chrome 1    gt           lt  customHeaders gt        lt  httpProtocol gt     lt  system webServer gt   lt  configuration gt       Microsoft recommends Edge mode since IE11  As noticed by Lynda  see comments   the Compatibility changes in IE11 recommends Edge mode      Starting with IE11  edge mode is the preferred document mode     it represents the highest support for modern standards available to the browser    But the position of Microsoft was not clear  Another MSDN page did not recommend Edge mode      Because Edge mode forces all pages to be opened in standards mode     regardless of the version of Internet Explorer     you might be tempted to use this for all pages viewed with Internet Explorer     Don t do this  as the X-UA-Compatible header is only supported starting    with Windows Internet Explorer nbsp 8    Instead  Microsoft recommended using  lt  DOCTYPE html gt       If you want all supported versions of Internet Explorer to open   your pages in standards mode  use the HTML5 document type declaration         As Ricardo explains  in the comments below  any DOCTYPE  HTML4  XHTML1     can be used to trigger Standards Mode  not only HTML5 s DOCTYPE  The important thing is to always have a DOCTYPE in the page   Clara Onager has even noticed in an older version of Specifying legacy document modes      Edge mode is intended for testing purposes only     do not use it in a production environment    It is so confusing that Usman Y thought Clara Onager was speaking about      The       example is provided for illustrative purposes only     don t use it in a production environment    lt meta http-equiv  X-UA-Compatible  content  IE 7 9 10   gt     Well    In the rest of this answer I give more explanations why using content  IE edge chrome 1  is a good practice in production     History  For many years  2000 to 2008   IE market share was more than 80   And IE v6 was considered as a de facto standard  80  to 97  market share in 2003  2004  2005 and 2006 for IE6 only  more market share with all IE versions    As IE6 was not respecting Web standards  developers had to test their website using IE6  That situation was great for Microsoft  MS  as web developers had to buy MS products  e g  IE cannot be used without buying Windows   and it was more profit-making to stay non-compliant  i e  Microsoft wanted to become the standard excluding other companies     Therefore many many sites were IE6 compliant only  and as IE was not compliant with web standard  all these web sites was not well rendered on standards compliant browsers  Even worse  many sites required only IE   However  at this time  Mozilla started Firefox development respecting as much as possible all the web standards  other browser were implemented to render pages as done by IE6   As more and more web developers wanted to use the new web standards features  more and more websites were more supported by Firefox than IE    When IE market sharing was decreasing  MS realized staying standard incompatible was not a good idea  Therefore MS started to release new IE version  IE8 IE9 IE10  respecting more and more the web standards      The web-incompatible issue  But the issue is all the websites designed for IE6  Microsoft could not release new IE versions incompatible with these old IE6-designed websites  Instead of deducing the IE version a website has been designed  MS requested developers to add extra data  X-UA-Compatible  in their pages   IE6 is still used in 2016  Nowadays  IE6 is still used  0 7  in 2016   4 5  in January 2014   and some internet websites are still IE6-only-compliant  Some intranet website applications are tested using IE6  Some intranet website are 100  functional only on IE6  These companies departments prefer to postpone the migration cost  other priorities  nobody no longer knows how the website application has been implemented  the owner of the legacy website application went bankrupt     China represents 50  of IE6 usage in 2013  but it may change in the next years as Chinese Linux distribution is being broadcast   Be confident with your web skills  If you  try to  respect web standard  you can simply always use http-equiv  X-UA-Compatible  content  IE edge chrome 1   To keep compatibility with old browsers  just avoid using latest web features  use the subset supported by the oldest browser you want to support  Or If you want to go further  you may adopt concepts as Graceful degradation  Progressive enhancement and Unobtrusive JavaScript   You may also be pleased to read What should a web developer consider     Do do not care about the best IE version rendering  this is not your job as browsers have to be compliant with web standards  If your site is standard compliant and use moderately latest features  therefore browsers have to be compliant with your website   Moreover  as there are many campaigns to kill IE6  IE6 no more  MS campaign   nowadays you may avoid wasting time with IE testing   Personal IE6 experience  In 2009-2012  I worked for a company using IE6 as the official single browser allowed  I had to implement an intranet website for IE6 only  I decided to respect web standard but using the IE6-capable subset  HTML CSS JS    It was hard  but when the company switched to IE8  the website was still well rendered because I had used Firefox and firebug to check the web-standard compatibility

User · Answer

Just for completeness  you don t actually have to add it to your HTML  which is unknown http-equiv in HTML5   Do this and never look back  first example for apache  second for nginx   Header set X-UA-Compatible  IE Edge chrome 1   add header X-UA-Compatible  IE Edge chrome 1

User · Answer

Use this to force IE to hide that annoying browser compatibility button in the address bar    lt meta http-equiv  X-UA-Compatible  content  IE edge    gt

[html] What does <meta http-equiv="X-UA-Compatible" content="IE=edge"> do?

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