AES, short for Advanced Encryption Standard encryption algorithm, is a symetrical key algorithm that can be used to encrypt electronic data. Symetrical key means that if you encrypt a setup package using AES and a secret password then your users must know the password in order to install your application. The password must be know by both parties, the party that encrypt (you) and the party that performs decryption (your clients).
AES algorithm is used with key sizes of 128, 192 or 256 bits. Longer keys provide better security. Advanced Installer uses 256 bits keys, so encrypted packages can protect sensitive data.
The security characteristics and its processing speed made from AES the current industry standard to encrypt large quantities of data.
Initially AES was called Rijndael based on the names of its developers, two Belgian cryptographers, Joan Daemen and Vincent Rijmen. The algorithm was adopted by the U.S. government with the name AES and it is used now worldwide.