State diagrams

It shows the dynamic behaviour of a system. The diagram shows the various states that an object can get into and the transitions that occur between the states.
State:
The state object is a snapshot of an object at a particular point in its life. A state may have an activity describing the function being performed.
Initial State:
The initial state is the starting state of the object with reference to the behaviour that the diagram explains. Each state diagram should have only one initial state.
Final State:
Each final state is the ending state of the object with reference to the behaviour that the diagram explains. There may be multiple final states for an object.
Transition:
The transition link represents the relationship between different states of an object. The transition guard is a condition which limits the cases in which a transition can occur. The transition action is performed during the transition and cannot be interrupted.