Objects have identity and are instances of classes. Fundamentally, objects are abstracted entities that encapsulate state and behavior. Classes are descriptions of objects with a common implementation. Classes are concerned with the implementation of uniform structural characteristics and behavioral characteristics. Fundamentally, classes are descriptions of objects with common attributes, operation implementations, semantics, associations, and interactions.
Types are descriptions of objects with a common specification.
Types are concerned with the specification of uniform structural characteristics and behavioral characteristics. Types may be explicitly related to classes, where a class receives an interface from a type and provides an implementation for the interface, or types may be implicitly related to classes, where a class defines an interface and provides an implementation. Fundamentally, types are descriptions of objects with common attributes, operation interfaces, semantics, associations, and interactions. There are various other concepts regarding objects and classes that are not discussed above. Return to Contents Links and Associations Links and associations abstract relationships among entities.