From there, you’ll see the splash screen of the version, and the build. The first 4 numbers in the year the build was released, (2010) The next 2 are the month of the release, (09-September), the next 2 are the day of the release, (03-third). The last four are the actual build number 2115, and the service pack number is new to the newer versions. Might not be shown for earlier versions.
I’ve seen fatal errors in Revit when teams are using the same version, but different build numbers, and users are syncing their builds local file to the central file, and the central file is receiving updates from multiple builds, when there have been some changes to the software code, and there is a discrepancy between two items, one new version, one old version, and Revit doesn’t know what to do.
In order to make sure everyone is using the same build, everyone should be using the latest build. For 2011, its build 20100903_2115 Web Update 2 Service Pack. For 2012, it’s build 20110916_2132 Update Release 2.