Microsoft is currently in the process of developing a new browser for Windows 10 codenamed 'Spartan', which will be a revamped and modernized version of Internet Explorer. One of the new features set to be included with the browser, finally, is proper support for extensions.
Although Internet Explorer 11 currently supports "add-ons", their usefulness and ability to truly enhance the functionality of the browser was limited. Meanwhile, two of the most popular browsers on the web - Mozilla Firefox and Google Chrome - have included wide extension support for years, which has helped them become well liked, feature-filled browsers.
At this stage Microsoft has only confirmed that there will be some form of extension support in Spartan, but it's expected that the implementation will be most similar to Chrome's. In fact it has been reported that Microsoft is looking in to some form of easy Chrome extension porting, which will be great for developers who don't want to recreate their extensions from scratch.
Spartan will feature a new, streamlined rendering engine called Edge, which is based on a heavily modified version of Internet Explorer 11's Trident engine. Other features already announced include an inking mode for annotating web pages, a new reading mode, and Cortana integration.
Spartan will ship with Windows 10, and some versions of the OS will include it alongside Internet Explorer 11 for compatibility reasons.