What shape typically represents a state in a state transition diagram?

In a state transition diagram, a state is typically represented by a circle or ellipse. This choice is significant because the circular or elliptical shape effectively illustrates the concept of a state as a distinct condition or situation in which an entity can exist at a particular point in time within a system.

The shape conveys a sense of continuity and allows the diagram to visually differentiate between various states, making it easier to follow the transitions which depict changes from one state to another in response to events or conditions. This clarity is crucial for modeling dynamic systems accurately, enabling better understanding of how systems react to inputs or changes over time.

Selecting a circle or ellipse aligns with standard practices in modeling techniques, such as Unified Modeling Language (UML), ensuring that the resulting diagrams are intuitively understood by stakeholders who are familiar with these conventions.