Basic Class Concepts
The class model describes data structure and is the UML model that is most relevant to databases. Classes provide the starting point for constructing class models.
An object is a concept, abstraction, or thing that has identity and meaning for an application. A UML object corresponds to an IE entity.3 An object is in or out of scope for a model, depending on its relevance to an application.
Application needs also determine the level of abstraction for representing an object. For example, an airplane flight can be represented by a departure/arrival time, a sequence of phases (at gate, boarding, taking off, enroute, landing, at gate, disembarking), or even more finely grained as a series of ground maneuvers and ...