What version of Android are you using? If you don't know go to your phone settings and phone information. It should say something like 2.3 or 2.3.6 or 4.0.1, something along those lines.
They are all the versions
Do you upgrade your phone much? Mine came with Gingerbread 2.3.5, I updated it to Ice Cream Sandwich as soon as it came out. I am on 4.0.3 at the moment.