Tor helps you anonymize the following:
web browsing and publishing, instant messaging, IRC, SSH, and other applications that use the TCP protocol
Essentially the Tor software bounces communications around to a variety of what they call “onion routers” and actually allows you to decide whether or not to identify yourself when you communicate.
You’ll just have to go to the site and read more about how people are using Tor to really understand it.
Tor is available for Win, Mac, and various Linux builds.