AES, or Advanced Encryption Standard, is a widely used encryption algorithm that secures data by converting it into a format that is unreadable without a specific key. It was established by the National Institute of Standards and Technology (NIST) in 2001 and is based on the Rijndael cipher, which was selected through a public competition. AES operates on fixed block sizes of 128 bits and supports key lengths of 128, 192, or 256 bits. It is commonly used in various applications, including securing communications, protecting sensitive data, and ensuring privacy in online transactions. Its strength and efficiency make it a standard choice for data encryption worldwide.