As Microsoft announced previously, Edge will be the default browser in Windows 10, while Internet Explorer will become a legacy option for compatibility reasons. Edge is supposed to be lighter and faster than Internet Explorer, but with new features such as a built-in notation tool, a distraction-free reading mode, and website information from Cortana.
The browser will also support extensions based on HTML and Javascript. Microsoft says developers will be able to port their extensions from Chrome with a few minor modifications, and showed off examples such as Reddit Enhancement Suite.
Why this matters: Microsoft's has made many attempts to convince people that Internet Explorer isn't terrible, but in the end the company has decided to make a clean break. Edge will be a major feature in Windows 10, and in addition to knowing how extensions will work in the new browser, we finally know what to call it.