1. Symmetric cryptography: Also known as secret-key cryptography, symmetric cryptography uses the same key for both encryption and decryption. A popular example of symmetric cryptography is the Advanced Encryption Standard (AES).
2. Asymmetric cryptography: Also known as public-key cryptography, asymmetric cryptography uses two different keys, one for encryption and one for decryption. A popular example of asymmetric cryptography is the RSA algorithm.