The document summarizes the Chord peer-to-peer lookup protocol. Chord provides efficient mapping of keys to nodes, scaling logarithmically. Each node maintains routing information for O(log N) other nodes. Lookup requires O(log N) hops, and joins/leaves require O(log^2 N) messages. Chord is decentralized, load balanced, and adapts to node joins, leaves, and failures while maintaining correctness. Simulation shows Chord is robust and lookup latency grows slowly with system size.