The Amnesic Incognito Live System or Tails is a Debian based Linux distribution aimed at preserving privacy and anonymity. Actually, it is the next iteration of development on the previous Gentoo based Incognito Linux distribution. All its outgoing connections are forced to go through Tor, and direct (non-anonymous) connections are blocked. The system is designed to be booted as a live CD or USB, and leaves no trace on the machine unless explicitly told to do so. The Tor Project has provided most of the financial support for development.
Tails is a live system that aims at preserving your privacy and anonymity. It helps you to use the Internet anonymously almost anywhere you go and on any computer but leave no trace using unless you ask it explicitly.
Tails comes with several built-in applications pre-configured with security in mind: web browser, instant messaging client, email client, office suite, image and sound editor, etc.