More from the Tails website:
Tails is a live operating system, that you can start on almost any computer from a DVD, USB stick, or SD card. It aims at preserving your privacy and anonymity, and helps you to:
- use the Internet anonymously and circumvent censorship; all connections to the Internet are forced to go through the Tor network;
- leave no trace on the computer you are using unless you ask it explicitly;
- use state-of-the-art cryptographic tools to encrypt your files, emails and instant messaging.