Tails is a live operating system that you can start on almost any computer from a USB stick or a DVD.

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.

https://tails.boum.org/