What it does: 

Tor protects you by encrypting your communications and bouncing them around a distributed network of relays run by volunteers all around the world. It works with many of your existing applications, including web browsers, instant messaging clients, remote login, and other applications based on the internet's TCP protocol.


It will not keep you anonymous if you visit websites that use Javascript or Flash (these plug-ins should be disabled). A lot of care must be taken even if you have Tor installed.

Suggested use: 

For activists who want to use the internet in countries that spy on and censor internet use.

Owned by: 

A non-profit organisation called the Tor Project.