1. Symmetric Encryption: Uses the same key for both encryption and decryption. It is fast and efficient but requires secure key management. 2. Asymmetric Encryption: Uses a pair of keys—a public key for encryption and a private key for decryption. It is more secure but slower than symmetric encryption. 3. Hashing: Converts data into a fixed-length string of characters, which cannot be converted back to the original data. It is often used for storing passwords.