State is any behavior pattern of the observable system, and state represents a behavior pattern of the system. Status specifies how the system responds to events. The states defined in the state diagram mainly include: initial state (initial state), final state (final state) and intermediate state.

An event is something that happens at a specific moment. It is an abstraction of external events that cause system actions or (and) transitions from one state to another.

Symbol In the state diagram, the initial state is represented by a solid circle, and the final state is represented by a pair of concentric circles (the inner circle is a solid circle).