OOAD, OOD , OOA

Object-oriented analysis and design (OOAD) is a software engineering approach that models a system as a group of interacting objects.
Each object is characterised by its class, its state (data elements), and its behavior

What is OOAD?
To emphasize considering a problem domain and logical solution from the perspective of objects

• OOA

Object-oriented analysis (OOA) applies object-modeling techniques to analyze the functional requirements for a system
OOA focuses on what the system does
Object-oriented analysis (OOA) is the process of analyzing a task (also known as a problem domain), to develop a conceptual model that can then be used to complete the task
A typical OOA model would describe computer software that could be used to satisfy a set of customer-defined requirements
During the analysis phase of problem-solving, a programmer might consider a written requirements statement, a formal vision document, or interviews with stakeholders or other interested parties.
The conceptual model that results from OOA will typically consist of a set of use cases, one or more UML class diagrams, and a number of interaction diagrams.

OOA : to find and describe the objects in the problem domain

• OOD

Object-oriented design (OOD) elaborates the analysis models to produce implementation specifications
OOD on how the system does it.
During object-oriented design (OOD), a developer applies implementation constraints to the conceptual model produced in object-oriented analysis
Concepts in the analysis model are mapped onto implementation classes and interfaces resulting in a model of the solution domain

OOD  to define logical software objects



Reference:
http://en.wikipedia.org/wiki/Object-oriented_analysis_and_design