My company is still using Internet Explorer 9 (yes, should be upgraded, we know) due to policy.
We now have a web application, which only works well when having set
<meta http-equiv="X-UA-Compatible" content="IE=Edge" />
My question
How does IE 9 know of the latest IE version (= Edge) as Edge did not exist when IE 9 came out? Via Windows Updates? Or...?
This is not what it seems, just a case of an overused word.
Firstly, Edge is not the latest version of Internet Explorer. It is a new browser that was forked from IE. It is "the latest IE version" the way that Chrome is the latest Webkit version.
The "Edge" that is referred to in that metatag is which rendering engine that should be used. It just means use the latest possible rendering engine (IE had the ability to fallback to previous rendering engines for compatibility reasons). In IE 9, this means force the site to be processed in IE 9 mode, and disregard any heuristic that may say that the site works better in IE 8.