In 2001, the National Institute for Standards and Technology (NIST) chose AES to secure sensitive information. Since then, AES has become the most widely used symmetric cryptosystem and has been intensively studied for vulnerabilities. In this survey, we celebrate twenty years of the AES by presenting an overview of cryptographers’ work on it. We describe the main cryptanalytic techniques on AES, including linear cryptanalysis, differential cryptanalysis, boomerang cryptanalysis, differential-linear cryptanalysis cryptanalysis, and many other techniques of cryptanalysis.