Describe the difference between symmetric and asymmetric encryption and provide scenarios where each is appropriate in web security.

Symmetric encryption uses a single key for both encryption and decryption, making it faster but requiring secure key exchange. Asymmetric encryption employs a public-private key pair, ensuring secure communication without a prior key exchange but being slower due to the complexity of operations. Symmetric encryption is suitable for data at rest, like stored files, while asymmetric encryption is ideal for secure communication over networks, such as SSL/TLS protocols.