The initial state is the state of an object before any events in the diagram have acted upon it.
An action state is a type of state that represents a completed activity.
A transition from an action state occurs when the action state's internal action is complete.
To indicate concurrent activities that must be completed before the next activity can occur, use a join transition.
Double-click transitions from action states to label them with guard conditions and action expressions.
To indicate activities that can occur in parallel, use a fork transition.
The final state represents the completion of activity in the situation the diagram represents.