State machine

State machine is a model of a system that describes the states of the system and the transitions between those states. Finite state machine (FSM) is a state machine with a finite number of states.

State Machine

• State - a condition or situation in the life of an object during which it satisfies some condition, performs some activity, or waits for some event (e.g. locked, unlocked)

• Transition represents the change in the system’s state in response to an event or condition (e.g. insert coin, push door)

• Event (input) - a trigger that causes a transition from one state to another (e.g. insert coin, push door)

• Action - an activity that is performed when a transition occurs (e.g. unlock, lock)