Build number

How to find the Build Number
From the Finder, choose About This Mac from the Apple menu. You will see the version number. Click on it and you will see the build number. Click on it again and you will get the serial number of the Macintosh.


 * For example: Mac OS X 10.1.5 -> Build 5S60a

Mac OS X 10.0.0 through version 10.0.4, as well as the Mac OS X Public Beta, displayed the build number along with the version number in the About This Mac window.