(OOD) Defining all of the types of objects necessary to communicate with people and devices in the system, showing how the objects interact to complete tasks, and refining the definition of each type of object so it can be implemented with a specific language or environment.

The objective of this phase is to design and refine the classes, attributes, methods, and structures that are identified during the analysis phase, user interface, and data access. This phase also identifies and defines the additional classes or objects that support implementation of the requirement.