more info:
"Tails or The Amnesic Incognito Live System is a security-focused Debian-based Linux distribution aimed at preserving privacy and anonymity. 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 DVD or live USB, and will leave no trace (digital footprint) on the machine unless explicitly told to do so. The Tor Project has provided most of the financial support for development. Laura Poitras, Glenn Greenwald, and Barton Gellman have each said that Tails was an important tool they used in their work with Edward Snowden"