Basic Association Concepts
Associations provide the means for relating classes. Associations are a prominent feature of the UML and are especially helpful for modeling databases.
A link is a physical or conceptual connection among objects. An association describes a group of links with common structure and semantics. An association describes a set of potential links in the same way that a class describes a set of potential objects. A UML link corresponds to an IE relationship and a UML association corresponds to an IE relationship type.5
The UML notation for an association is a line (possibly with multiple line segments) that connects the related classes. The line between Customer and Address in Figure 4.1 is an ...