Microsoft Visual Studio versioning:

Visual Studio 9 is marketed as Visual Studio 2008
Visual Studio 10 is marketed as Visual Studio 2010
Visual Studio 11 is marketed as Visual Studio 2012
Visual Studio 12 is marketed as Visual Studio 2013

I’m currently working with all of these and it makes my brain hurt; some scripts use the internal names and some the marketing names.

Not to forget that the C/C++ compiler in VS 2008 is version 15 and the one in VS 2013 is version 18.