Tor is (or was at one point) an acronym for "the onion router". It encrypts and relays your online activity "through a network of systems run by volunteers in various locations" making anonymity easy and getting you around most remote web filters. With tor, you get: Online anonymity Uncensored internet access Access to .onion URLs (granted, many of these are child pr0n). More about it here and here. I2P is similar. Rather than .onion, you have .i2p. More here and here. It's easy to run exit or relay nodes for these programs, so if you have access to unfiltered, uncensored internet, you can help those who don't get around their filters. Tor is often used in China to get around the Great Firewall. Just thought this deserved mention.