Windows Phone 8

Windows Phone 8 (codenamed 'Apollo') is a version of the Windows Phone mobile operating system. This is the first version based off of the Windows NT kernel instead of Windows CE, being developed as a version of Windows 8 in concurrency with it.

Windows Phone has its own versioning system. The build of Windows NT that a given build is based on is stated in the build's page.

Update system
Windows Phone 8.x updates are distributed via Windows Update as CABs with three different extensions: a file of type  is a full package, a file of type   is an update package containing   delta compressed files from a previous build, and a file of type   is a removal package.