Microsoft announced today that its new OS will be called Windows 10 - and not Windows 9, as had been widely expected. The company also unveiled its new Windows Insider Program, and confirmed that the new OS will be available for early adopters and its "most enthusiastic" users to download tomorrow. But when will the OS actually begin rolling out to customers? Microsoft isn't yet committing to a firm date, but has said that it plans to release the full version of Windows 10 around the middle of next year.

In a video uploaded to YouTube and shared on Microsoft's official Windows blog, Joe Belfiore, leader of the Windows product definition and design team, guides the main changes people can expect in the preview. Some of the biggest changes include the task view and snap assist features revealed today. Additionally, the preview will feature the return of the Start menu to Windows, a feature heavily requested by users.