TOR is a network tool that allows you to improve your privacy and security on the internet. Using Tor helps stop a kind of surveillance called traffic analysis, which is used to detect who is communicating with each other over the internet. There is even a stand-alone browser available for download.

Tor can be used to keep websites from tracking you or to connect to news sites or instant messaging services that are blocked by local Internet providers. Tor's services also let users publish to websites without needing to reveal their location or the location of the site they are posting to -- making it very suitable for sensitive material.

Enabling safer communication by anyone working in insecure or restrictive environments, like activists, whistleblowers, investigative journalists, bloggers and human rights defenders
Allowing rights advocates to connect to websites without the danger of notifying authorities

Easy to set up in open browsers like Firefox

Can dramatically slow down internet connection speeds
Some websites and services are difficult or impossible to use with TOR enabled

Windows, Mac OSX, Linux

Security-in-a-box: Orbot

Security-in-a-box: Orweb

For Android:

Orbot homepage

Orweb homepage