Define objects in a graphical system.

• A graphical system consists of objects and actions. Objects are what people see on the screen as a single unit.
• Objects can be composed of subobjects. For example, an object may be a document and its subobjects may be a paragraph, sentence, word, and letter.
• Objects are divided into three meaningful classes as Data objects, which present information, container objects to hold other objects and Device objects represent physical objects in the real world.
• Objects can exist within the context of other objects, and one object may affect the way another object appears or behaves. These relationships are called collections, constraints, composites, and containers.