An association is a structural relationship between two or more classes in a UML class diagram.
It shows how objects of these classes can connect. For example, an association can link a Person class to an Address class.
Association names describe the relationship. Moreover, role names explain the function of each association end. Multiplicities define how many objects may participate. For example, the multiplicity 1 requires one object, while 0..* allows any number of objects.
Teams can also define the direction in which objects navigate the relationship. Therefore, associations help clarify which objects a system can access from another object.
An association class adds attributes to the relationship itself. For example, it can store the creation date of a connection. However, a normal class with separate associations may provide a clearer model.
Associations describe structure, responsibilities, navigation paths, and quantitative constraints between classes. As a result, they support precise data models and requirements.
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