File with an .AES extension contains any file coded with the 256-bit AES coding algorithm and a password file. It is often used to transfer confidential private and business documents. The AES tension is most often added on the end of the original filename.

The AES extension is used by file encryption programs, out of which a popular one is AES Crypt. It creates files which can be double-clicked, and after giving a proper password, the original content can be reached.