Architecting and designing : UML 2.5 : Model Elements : Classifiers : State Machine
  
State Machine
UML specifies several types of behaviors:
Activity
State Machine
Interaction
Opaque Behavior, which has subtype FunctionBehavior
A State Machine is a model of the States that an object can be in, and how it transitions to different States.
See also
Activity
Actor
Association
DataType
Enumeration
Extension
FunctionBehavior
Information Item
Interaction
Interface
Opaque Behavior
Primitive Type
Signal
Stereotype
Use Case
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Classifiers