The Onion Router, more commonly known as just Tor, is a cryptographic network of computers that seeks to provide anonymity to its users. Users connect to a Tor “entry node,” and tell it what Internet sites they want to access. That request is then passed through a series of encrypted links, bouncing around unpredictably, until it finds an “exit node,” and then that server (likely nowhere near the user) then makes the request, and the results are sent back through the network.
http://www.redstate.com/2014/09/16/tech-night-isps-wary-tor/