Pseudostate – the starting point of a state machine, indicated by a black dot.
Origin state – the original state of an object from which the transition occurs.
Destination state – the state to which an object moves after the completion of a transition.
Message event – the trigger for a transition, which causes the object to leave the origin state.
Guard condition – a true/false test to see whether a transition can fire.
Action expression – a description of the activities performed as part of a transition.