AEAD (Authenticated Encryption with Associated Data) cipher is a type of encryption algorithm that ensures both the confidentiality and the integrity of data. Unlike traditional encryption methods that only protect the secrecy of the data, AEAD ciphers also authenticate the data, meaning they can detect if any part of the message has been tampered with. Additionally, AEAD allows for the inclusion of associated data - information that needs to be authenticated but not encrypted, such as headers. AEAD ciphers are widely used in modern secure communication protocols like TLS and IPsec to protect data in transit from eavesdropping and unauthorized modification.