What is a State Machine?

A State Machine is a model of system behavior that describes its operation through a finite number of states and transitions between them. In each state, the system can perform certain actions, and transitions occur in response to events or conditions.

Example: a vending machine with three states — waiting for coin, selecting product, dispensing product. When a coin is inserted, the machine transitions from the waiting state to the selecting state, then after selection — to dispensing, and back to waiting.

State Machine helps formalize logic, make the system predictable, and facilitate testing and maintenance.