The Tor Browser Bundle is a software tool designed to increase the privacy and security of your Internet activities and habits. It masks your identity and your on-line browsing from many forms of Internet surveillance. Tor can also be useful as a secure means of circumventing electronic restrictions so that you may access or publish blogs and news reports.
Tor protects your anonymity by routing communications through a distributed network of servers run by volunteers from all over the world. Using Tor hides the sites you visit from potential onlookers, and hides your location/identity from those sites. The software is designed also to make sure servers in the Tor network don't know both your location and the sites you are visiting.
Tor also takes steps to encrypt the communication to and through its network, but this measure can not extend all the way to a website which is sending or receiving content over non-encrypted channels (i.e. not providing https access). Nevertheless, the advantage of using Tor when accessing such sites is that Tor can secure your communication up to the step between the last of the Tor servers and the non-secure site. This confines the chance to intercept the content to that last step.
The Tor Browser Bundle consists of the Tor software and a modified version of the Firefox web browser, which is designed to provide extra protection while using it. The browser bundle also includes NoScript and HTTPS-Everywhere add-ons.
Note: There is a trade-off between anonymity and speed. Because Tor facilitates anonymous browsing by bouncing your traffic through volunteers' computers and servers in various parts of the world, it will definitely be slower than using other web browsers on your computer.