A class diagram models the static view of a system. It comprises of the classes, interfaces, and collaborations of a system; and the relationships between them.
The UML Class diagram is a graphical notation used to construct and visualize object oriented systems. A class diagram in the Unified Modelling Language (UML) is a type of static structure diagram that describes the structure of a system by showing the system's:
• classes,
• their attributes,
• operations (or methods),
• and the relationships among objects.