Tails is a Debian-based Live Linux operating system designed for privacy and anonymity. In addition to no-trace Internet browsing via Tor, other applications configured for privacy include:
Iceweasel web browser with HTTPS Everywhere
Pidgin messenger
Claws mail client
KeePassX password manager
GnuPG data encryption
I2P anonymizing network
TrueCrypt disk encryption.
Everyday functionality is provided by applications such as:
OpenOffice
GIMP
Scribus
Audacity
PiTiVi
Sound Juicer
Brasero
...
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The Tails Live system runs from a DVD, USB stick, or SD card and uses only RAM for storage, leaving your hard disk untouched. Geared toward preserving privacy and anonymity, Tails comes with an impressive set of cryptographic tools. All connections to the Internet go through the Tor network. The Tor anonymity network is designed to leave no trace and prevent surveillance of your online activities.
CentOS describes itself as "… a community-supported distribution derived from sources freely provided to the public by Red Hat for Red Hat Enterprise Linux (RHEL)." Tails is a specialty Live Linux system designed for easy access to the TOR anonymity network.