What does Spyware do exactly?
 

i'm just curious, lots of people told me different things, and i got the search and destroy thing..

Just as the name suggests, it collects information about you and the things you do on your computer without your knowledge. It spys on you.

It also keeps building up and takes up a lot of your memory. Some of them can even screw up your internet connection.

Basically, it's not something you want on your computer.

www.spywareinfo.com has a great article, and the answers to your question.