OP (stands for original poster, in case OP doesn't know), RAM stands for Random Access Memory. I don't know the specifics, but it's used to hold temporary information that every program generates when running.

Other than that, while those guys are being blunt, they do have a point: You should get used to looking for basic information (this is like Computer Science 101) such as this by yourself.

edit: Here, lots of topics on subject
http://en.wikipedia.org/wiki/Special...m+memory&go=Go