Asymmetric encryption, also known as public key encryption, is so named because it uses a pair of keys to encrypt and decrypt messages. The two keys are known as a public key and a private key, and they are mathematically related so that messages encrypted with one key can only be decrypted with the other. The public key can be freely shared with others, allowing anyone to send encrypted messages to the owner of the key pair, while the private key must be kept secret to ensure the security of the encrypted messages.