Advanced Encryption System makes use of the AES Encryption Standard. This standard has been adoted by many companies and agencies to help keep their information secure. AES256 is currently th CIA's primary encryption Algorithm for classified documents. The reason for this is that AES is only decipherable if you are in possesion of the password that was used to encrypt the data. This password can then be used again to decrypt the information.
Advanced Encryption System allows you to make use of this extremely secure encryption algorithm to encrypt your everyday documents and notes. Many applications allow you to encrypt your information however very few are completely free and still fully functional.