In theory, including <meta http-equiv=”X-UA-Compatible” content=”IE=edge”> forces IE to display your HTML using “Standards Mode” (as opposed to “Quirks Mode”), making it more inline with other modern browsers. However, as @David’s answer points out, unless you’re hosting a site in the “Local Intranet” zone, there is very little reason to include it and, according to … Read more
If you support IE, for versions of Internet Explorer 8 and above, this: <meta http-equiv=”X-UA-Compatible” content=”IE=9; IE=8; IE=7″ /> Forces the browser to render as that particular version’s standards. It is not supported for IE7 and below. If you separate with semi-colon, it sets compatibility levels for different versions. For example: <meta http-equiv=”X-UA-Compatible” content=”IE=7; IE=9″ … Read more
If you need to override IE’s Compatibility View Settings for intranet sites you can do so in the web.config (IIS7) or through the custom HTTP headers in the web site’s properties (IIS6) and set X-UA-Compatible there. The meta tag doesn’t override IE’s intranet setting in Compatibility View Settings, but if you set it at the … Read more
November 2021 Update As this answer is now 10+ years old my recommendation would be to leave this tag out altogether, unless you must support old legacy browsers. 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 … Read more