UML Building blocks - Relationships

Relationships

Dependency

A dependency is a using relationship that states that a change in specification of one thing may affect another thing that uses it, but not necessarily the reverse.

Association

An association is a structural relationship that specifies that objects of one thing are connected to objects of another.

Aggregation

An aggregation is a special form of association that specifies a whole­part relationship between the aggregate (the whole) and a component (the part).

Generalization

A generalization is a relationship between a general thing and a more specific kind of that thing. Sometimes it is called an ''is ­a­ kind­ of'' relationship.

Realization

A realization is a semantic relationship between classifiers, wherein, one classifier specifies a contract that another classifier guarantees to carry out.