Tor

Tor is a widely used, free software program that allows users to communicate anonymously on the Internet by sending messages through a vast worldwide series of relays (“onion routing”). At each step, messages are encrypted, making it successively more difficult to trace their origins. The name is derived from the acronym for the original program, The Onion Router. Tor users can send email, post on message boards or in chat rooms, and visit webpages without fear of discovery, for better or worse. Its anonymity has led free speech advocates to celebrate it as a means of preserving privacy and opposing censorship, but that same anonymity can be used to hide illicit activities. This entry examines Tor’s uses, history, and impact on Internet communications.