UML 2.0 in a Nutshell

Relationships

Classes in isolation would not provide much insight into how a system is designed. UML provides several ways of representing relationships between classes. Each of UML relationship represents a different type of connection between classes and has subtleties that aren't fully captured in the UML specification. When modeling in the real world, be sure that your intended viewers understand what you are conveying with your various relationships. We say this both as a warning to the modeler and as a slight disclaimer that the following explanations are our interpretation of the UML specification. For example, the debate over when to use aggregation versus composition is ongoing. To help determine which relationship is most appropriate, we offer a short phrase for each type that may help make the distinction. Again, the important thing is to be consistent within your model.

Dependency

The weakest relationship between classes is a dependency relationship. Dependency between classes means that one class uses, or has knowledge of, another class. It is typically a transient relationship, meaning a dependent class briefly interacts with the target class but typically doesn't retain a relationship with it for any real length of time.

Dependencies are typically read as "...uses a...". For example, if you have a class named Window that sends out a class named WindowClosingEvent when it is about to be closed, you would say "Window uses a WindowClosingEvent."

You show a dependency ...