Build tag

A build tag or buildtag is a common name for the version string format used by recent version of Microsoft Windows. In its fully expanded form, the build tag is a unique identifier of a Windows compile that includes the full version number, target architecture and build type, branch or lab name, account username for private builds, and compilation timestamp.

Build tags started to be introduced towards the end of Windows 2000 development, although they were not inserted into Windows builds themselves until very early in the development of Windows XP.