Consistent Hashing
In plain terms
A technique for distributing data across nodes that minimizes reshuffling when nodes change.
Going deeper
Consistent hashing maps keys and nodes onto a ring so adding or removing a node only moves a small fraction of keys, not everything. It's key to scalable caches and distributed databases.
Under the hood
Virtual nodes smooth uneven key distribution; adding/removing a node only remaps keys near it on the ring, minimizing data movement.
Examples
Distributed caches (memcached), Cassandra/DynamoDB partitioning, load balancers.
Think of it like...
Like seating guests around a round table by name: adding one more chair only nudges a few neighbors instead of reseating the entire table.