Object-oriented Design (OOD) is an important activity in most (object-oriented) software development lifecycle models:
The goal of OOD is to produce a model of the system from the developer's perspective (the design model). In particular, the design model captures the internal structure and interactions of the system. The design model is the starting point for object-oriented programming or implementation. The starting point for OOD is the functional specification, which is the output of the requirements activity. The functional specification models the system from the user's perspective. Object-oriented Analysis (OOA) is an important sub-activity of the requirements phase.
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