the beauty of uml is that most things are optional we only need to specify as much information in diagram as makes sense for the current situation in quick whiteboard sessionwe might just quickly draw lines between boxes in formal documentwe might go into more detail in the case of apples and barrelswe can be fairly confident that the association ismany apples go in one barrelbut just to make sure nobody confuses it withone apple spoils one barrelwe can enhance the diagram as shownorange basket go in go in apple barrel this diagram tells us that oranges go in baskets with little arrow showing what goes in what it also tells us the number of that object that can be used in the association on both sides of the relationship one basket can hold many (represented by *orange objects any one orange can go in exactly one basket this number is referred to as the multiplicity of the object you may also hear it described as the cardinality these are actually slightly distinct terms cardinality refers to the actual number of items in the setwhereas multiplicity specifies how small or how large this number could be frequently forget which side of relationship the multiplicity goes on the multiplicity nearest to class is the number of objects of that class that can be associated with any one object at the other end of the association for the apple goes in barrel associationreading from left to rightmany instances of the apple class (that is many apple objectscan go in any one barrel reading from right to leftexactly one barrel can be associated with any one apple specifying attributes and behaviors we now have grasp of some basic object-oriented terminology objects are instances of classes that can be associated with each other an object instance is specific object with its own set of data and behaviorsa specific orange on the table in front of us is said to be an instance of the general class of oranges that' simple enoughbut what are these data and behaviors that are associated with each object[