Paxos
termcloudprogramming
Leslie Lamport's consensus algorithm, the first proved correct for an asynchronous network where machines may fail, and the basis of most replicated systems built since.
It is famous for two things: being correct, and being hard to understand from the paper, which was written as an allegory about a fictional Greek parliament and took years to be taken seriously. Barbara Liskov and Brian Oki reached an equivalent design independently at about the same time. Most production systems run a variant rather than the original, and Raft was designed explicitly to be the same guarantee explained more simply - which is a rare case of a field admitting that comprehensibility is a property worth optimising.
Also known as: multi-paxos