Using Tor makes it more difficult to trace a user's Internet activity. It directs Internet traffic via a free, worldwide, volunteer overlay network that consists of more than seven thousand relays. Tor, short for The Onion Router, is free and open-source software for enabling anonymous communication. Comparison of Internet Relay Chat clients.Overlay network, mix network, onion router, Anonymity application Unix-like, ( Android, Linux, BSD, macOS), Microsoft Windows, iOS