<meta http-equiv = "x-ua-compatible" content = "ie=edge,chrome=1" >

1.x-ua_compatible is a newly added setting for IE8, in order to handle compatibility. X-ua-compatible file header supports IE8 or later versions. With emulate is used for simulation simulations.

2. The mode priority specified in the Web page is higher than the mode specified by the HTTP header in the server.

3. Why use x-ua-compatible? When IE8 just launched, many web pages due to the problem of refactoring, unable to adapt to the higher level of the browser, so use the x-ua-compatible tag force IE8 to be rendered in a low-version manner.

4. Label Explanation:

4.1<meta http-equiv = "x-ua-compatible" content = "ie=7" > The above code tells IE browser whether or not to declare the document standard with DTD, <! DOCTYPE>,IE8/9 will render the page with the IE7 engine.

4.2<meta http-equiv = "x-ua-compatible" content = "Ie=8" > The above code tells IE Browser, IE8/9 will render the page with the IE8 engine.

4.3<meta http-equiv = "x-ua-compatible" content = "Ie=edge" > The above code tells IE Browser, IE8/9 and later versions will render the page with the highest version of IE.

4.4 If separated by semicolons (;), there are different compatibility for different browser versions, for example:

<meta http-equiv = "x-ua-compatible" content = "ie=7;ie=9" > Renders IE8 and IE7 according to IE7 Standard, but IE9 is rendered according to IE9 standard. It allows for different backwards compatibility levels.

4.5<meta http-equiv = "x-ua-compatible" content = "ie=edge,chrome=1" > above code ie = Edge tells IE to render Web pages with the latest engine, chrome = 1 Activates C Hrome Frame. the chrome=1 here is not to say that IE's technology is augmented by the ability to emulate chrome, but rather with Google Chrome frame, the Google embedded browser framework GCF. This plugin can make the user's IE browser look the same, but the user actually uses the chrome kernel when browsing the Web page, and supports Windows XP and the IE6/7/8 of the above system. Google this corner digging really to force!
gcf:http://code.google.com/intl/zh-cn/chrome/chromeframe/

5. An interesting fact is that after setting the <meta http-equiv= "x-ua-compatible" content= "Ie=edge" >, even if not declared! DOCTYPE, in IE8, IE9, the page will not enter the weird mode.

Reference Link: http://zccst.iteye.com/blog/2162187

http://blog.csdn.net/yimuqing123/article/details/53012549

https://msdn.microsoft.com/zh-cn/library/cc288325

Http://www.cnblogs.com/victor5230/p/5846832.html

<meta http-equiv = "x-ua-compatible" content = "ie=edge,chrome=1" >