The original version of Windows 11 (also retroactively namedversion 21H2 and codenamed "Sun Valley") was released in October 2021.[1][2] It carries the build number 10.0.22000.[3] It was retroactively named "version 21H2" by Microsoft per its naming conventions that are labeled "YYHX", with YY representing the two-digit year and X representing the half-year of planned release (for example, version 21H2 refers to builds which initially released in the second half of 2021).[4]