Poly1305 is a cryptographic message authentication code (MAC) designed to provide data integrity and authenticity. It was created by Daniel J. Bernstein in 2005 and is known for its efficiency and security. Poly1305 uses a one-time key and a polynomial evaluation to generate a unique tag for each message, ensuring that any alteration to the message can be detected. The algorithm operates in a simple manner, taking a message and a secret key to produce a fixed-size output. It is often used in conjunction with other cryptographic systems, such as ChaCha20, to secure communications in various applications, including secure messaging and data storage.