State diagram

A state diagram is an fundamental concept in computer science. States are nodes that have arrows that leave them for other notes. There is typically a unique starting state. Transitions are caused in general by some event. Often events are represented by particular messages. In the example, the messages a,b and c causes transitions between states in our set of states: {Start, State_1, State_2, Stop}. Our message alphabet is the set: {a,b,c}.

In Standard Unified_modeling_languge, the start state is a solid circle. The end state is a solid circle with a circle around it. States are rounded rectangles.

/\        /\     ● -> | State_1 | -> | State_2 | -> ◉ a    \/   b     \/    c

Also see
Finite_state_machine Automota