Tor is a toolset for a wide range of organizations and people that want to improve their safety and security on the Internet. Using Tor can help you anonymize web browsing and publishing, instant messaging, IRC, SSH, and other applications that use the TCP protocol. Tor also provides a platform on which software developers can build new applications with built-in anonymity, safety, and privacy features.
Your traffic is safer when you use Tor, because communications are bounced around a distributed network of servers, called onion routers. Tor's technology aims to provide Internet users with protection against "traffic analysis," a form of network surveillance that threatens personal anonymity and privacy, confidential business activities and relationships, and state security.
Instead of looking at the content of your communications, traffic analysis tracks where your data goes and when, as well as how much is sent. Tor aims to make traffic analysis more difficult by preventing websites, eavesdroppers, and even the onion routers themselves from tracing your communications online. This means Tor lets you decide whether to identify yourself when you communicate.