One of the most popular problems to be solved in modern IT systems is that of keeping the state of your application distributed across a number of machines.

Paxos is one of the algorithms that solves this problem by giving you a protocol that allows the sets of machines to agree upon a set of operations that would all be applied to their states thus giving you a set of machines in the same state.

A simple example, is if you had a set of 3 machines starting with state of “0” and wanted to add “1” to their state. Paxos would define how they should communicate so that in the end, even if one of the machines failed during execution, would all end up with a state of “1”.