5466.5.x86fre.winmain.060627-2030
5421.3.x64fre.winmain.060428-1903
5231.6.winmain_idx03.051004-2120

Do any of those make sense? To a lot of people, they don’t and it’s understandable. These are build strings, of which are seen in each build of Windows Vista in the About Windows dialog (Start , Run, type winver then press OK). Here’s how to dissect and understand what the build string means in it’s different sections. Each part of the string’s colour coordinates with the same colour below with the explanation for what that particular bit means.

5472.5.winmain_idx01.060713-1900

Build number - how many “compilations” of the operating system’s different bits from the original build. For example, Vista started out as Windows Server 2003 originally which has a build number of 3790, which means there have been 1,682 compilations since that including build 5472.

Sub-build number - Essentially it means the number of times that the particular build has been compiled. This can be for a number of reasons such as something was missed out, or there was a bug which was obvious and needed to be fixed before release.

Build branch - The main branch of builds. Imagine this - loads of teams working on separate things within Vista, but they all come together as “winmain”. Essentially where the build came from.

Sub-build branch - In this particular build (5472) and most other Vista builds, the idx is a special set of branches which comes off the winmain one - it basically means that it’s reached a quality of which it can be released to testers. Just another extension of where the build actually came from.

The date built - This comes in the format of YY/MM/DD (US standard), which basically means 2006 July 13th.

The time of the build - This comes in international 24-hour clock standard - 19:00 hours (7pm) Redmond time.