How can you tell if your mac has os x?

Answer:
Selecting About This Mac from the Apple menu (top left corner) will open a window which will give details of the Mac OS that is being used. At a glance if the window you are looking at has a red, amber and green buttons in the top left corner then it is Mac OS X.
First answer by Homework Doer. Last edit by Homework Doer. Contributor trust: 268 [recommend contributor recommended]. Question popularity: 15 [recommend question].