Finite State Machine

• A mathematical model of an entity that describes its behavior as a result of its past history and current inputs.
• Finite state machines (FSM’s) are machines (generally computer programs) which proceed in clearly separate and discrete steps from one to another of a finite number of configurations or states.
• a machine with a fixed number of states and no memory, eg the processor in a Turing Machine; used as a theoretical basis for creating efficient algorithms for, eg, communication protocols, lexical analysis and pattern matching.
• A finite state machine (FSM) or finite state automaton (plural: automata) is a model of behavior composed of a finite number of states, transitions between those states, and actions.