States can be distinguished by the values of certain attributes and/or the existence of links [Detsis, 2000].

State transition diagrams are generated during analysis to capture the behaviour of objects displaying complex dynamic behaviour (and as an extend the overall behaviour of a system or a subsystem). There is no need to generate state transition diagrams for classes that demonstrate very little dynamic behaviour.

Activity diagrams may be used to elaborate on use cases, to specify complex object behaviour that exhibits a procedural flow of control, as flowcharts to specify algorithmic design for class operations or to understand multithreading [Detsis 2000; Fowler, 2000a].