Microsoft is committed to providing an interoperable web by supporting modern web standards. Doing this lets developers use the same markup across web browsers, helping to reduce development and support costs.
Supported web standards include:
Web Graphics Library (WebGL)
Canvas 2D L2 extensions, including image smoothing using the nearest neighbor, dashed lines, and fill rules
Fullscreen API
Encrypted media extensions
Media source extensions
CSS flexible box layout module
And mutation observers like DOM4 and 5.3
For more information about specific changes and additions, see the IE11 guide for developers.