Finite-state machine

Summary

A finite-state machine is an abstract machine that is in one of finitely many states at each moment. It changes state each time it reads an input symbol. With a set of accepting states it becomes a deterministic finite automaton, which accepts or rejects words. With an output function it becomes a Mealy machine or a Moore machine, which translates input words into output words. Finite-state machines are the simplest models of computation in automata theory and model many real devices, such as vending machines and network protocols.