Main Features:

-Creates a virtual encrypted disk within a file and mounts it as a real disk.
-Encrypts an entire partition or storage device such as USB flash drive or hard drive.
-Encrypts a partition or drive where Windows is installed (pre-boot authentication).
-Encryption is automatic, real-time (on-the-fly) and transparent.
-Parallelization and pipelining allow data to be read and written as fast as if the drive was not encrypted.
-Encryption can be hardware-accelerated on modern processors.
-Provides plausible deniability, in case an adversary forces you to reveal the password:
-Hidden volume (steganography) and hidden operating system.

Home page -http:///www.truecrypt.org/