Determine Which Application Version You Are Using (Mac)

Notice in this example we are using iTunes.  However, this same procedure would work for any application. 

1. Activate iTunes by clicking on the iTunes Application icon in your "Applications" folder, alternatively it might be located in your Dock.  
2. While "iTunes" is still activated (you know it is activated because it says "iTunes" in the menu bar next to the Apple logo, see the previous picture for a screenshot) click on the "iTunes" text in the menu bar, and select "About iTunes". 
3. At this point a dialog window will appear with the version information for iTunes. In this case we see that we are running iTunes Version 8.1.