Explain consistent hashing and its advantages for distributed systems.

Consistent hashing maps both keys and servers to a circular hash space (ring). Keys are assigned to the next server clockwise. When a server joins/leaves, only K/n keys need remapping (K=keys, n=servers) versus all keys in traditional hashing. Virtual nodes (multiple positions per server) improve load balance. Used in distributed caches (Memcached), databases (DynamoDB, Cassandra), and CDNs for scalable data distribution.