In Object-oriented programming, Association defines a relationship between classes of objects which allows one object instance to cause another to perform an action on its behalf.
In generic terms the causation is usually called "sending a message" to the controlled object. Concrete implementation usually requires the requesting object to invoke a method or member function using a reference or pointer to the memory location of the controlled object.
The objects that are related via the association are considered to act in a role with respect to the association, if object's current state in the active situation allows the other associated objects to use the object in the manner specified by the role. A role describes the public aspects of an object with respect to an association.
See also: Aggregation, Inheritance.gffggfgfgfg
