A Key Encapsulation Mechanism (KEM) is a cryptographic protocol designed to securely exchange encryption keys between parties over an insecure channel. Instead of directly sharing a secret key, KEM allows one party to generate a random key and encapsulate it using the recipient's public key. The recipient then decapsulates the message using their private key to retrieve the secret. This process ensures that only the intended recipient can access the key, providing confidentiality and security. KEMs are widely used in hybrid encryption schemes and are important in post-quantum cryptography due to their resistance to quantum attacks.