Classes
In UML, a class represents an object or a set of objects that share a common structure and behavior. Classes, or instances of classes, are common model elements in UML diagrams.
Class model element
The name of a class, which you should be able to derive from the vocabulary of the system that you are modeling, reflects its role, or one of its roles, in the system. As the following figure illustrates, the class model element is represented as a rectangle with three compartments:
Show or hide the attributes and operations of a class
You can specify whether or not to display the attributes and operations. You can choose to display all or only selected attributes and operations.

Note: You can set to show or hide
the attributes and operations at individual instance of the class, hence you can define the display
to vary at different instances.