The Class diagram captures the logical structure of the system - the Classes - and things that make up the model. It is a static model, describing what exists and what attributes and behavior it has, rather than how something is done.
Illustrate relationships between Classes and Interfaces. Generalizations, Aggregations and Associations are all valuable in reflecting inheritance, composition or usage, and connections, respectively.
Example Diagram: Example Class Diagram
Select Class diagram elements and connectors from the Class pages of the Toolbox.