Internet Explorer 10 is a fast browser with good standards compliance, and the version of Internet Explorer 10 included with Windows Phone 8 is no exception, as it's almost identical to its desktop sibling. But Internet Explorer 10 has a problem: Web developers don't expect to see it on the mobile Web. The mobile Web is dominated by WebKit-based browsers, and mobile sites tend to be developed exclusively for, and tested exclusively on, WebKit browsers. A similar problem exists for tablets.
Often the development is even narrower; although both Android and iOS sport WebKit-based browsers, iOS is the one that dominates mobile browser usage, and dominates testing as a result.
This situation is all rather familiar; WebKit, especially on iOS, is occupying a similar position to that once held by Internet Explorer 6 on the desktop, where Web content was "best viewed in Internet Explorer 6" and was prone to breaking in Netscape or Firefox.
Keen to avoid being left out, Microsoft is imploring Web developers to adapt their sites. In a recent blog post, the software giant explains a variety of ways in which devs can update their sites to work well in browsers other than WebKit. Key to this was proper handling of incompatible features.