TrueCrypt is a software system for establishing and maintaining an on-the-fly-encrypted volume (data storage device) No data stored on an encrypted volume can be read (decrypted) without using the correct password/keyfile(s) or correct encryption keys. Encryption does not mean it has to be slow or difficult. In fact, TrueCrypt makes it really fast and you can access all files as if they were unencrypted. If you need more protection, simply create an encrypted container and store your files on a flash drive.”]
Source: http://www.shoaibyousuf.com/2012/01/how-to-encrypt-and-password-protect.html