AES is a standard, sponsored by the National Institute of Standards and Technology, for protecting data through encryption.
AES supports key sizes of 128 bits, 192 bits and 256 bits and will serve as a replacement for the Data Encryption Standard (DES), which has a key size of 56 bits.
In addition to the increased security that comes with larger key sizes, AES can encrypt data much faster than Triple-DES, a DES enhancement that which essentially encrypts a message or document three times. According to NIST's AES overview: "The AES algorithm is a symmetric block cipher that can encrypt (encipher) and decrypt (decipher) information." It is based on the Rijndael algorithm, named for Belgian researchers Vincent Rijmen and Joan Daemen, who developed it.