What is the difference between symmetric and asymmetric encryption?

Symmetric encryption uses the same key for both encryption and decryption, making it fast and efficient for large data volumes. Examples include AES, DES, 3DES, and Blowfish. The challenge is key distribution since both parties must securely share the secret key. Asymmetric encryption uses a mathematically related key pair: a public key for encryption and a private key for decryption. Examples include RSA, Elliptic Curve Cryptography, and Diffie-Hellman. Asymmetric is slower but solves the key distribution problem.