alexandraerin

Aero is part of Vista- it's basically Microsoft saying, "You know, all these people have these really fancy computers and really powerful video cards. Why don't we have the operating system use more of that power." Thus, they created Aero- basically a Windows desktop where the frame around an application looks like it's made of glass, so you can see what's behind it.

This is Aero. Or at least what it looks like. There's more to it, but that's the most easily identified aspect.