Object Oriented Analysis and Design is a structured method for analyzing and designing a system by applying object-oriented concepts. This design process consists of an investigation into the objects constituting the system. It starts by first identifying the objects of the system and then figuring out the interactions between various objects.

The process of OO analysis and design can be described as:

• Identifying the objects in a system;
• Defining relationships between objects;
• Establishing the interface of each object; and,
• Making a design, which can be converted to executables using OO languages.

We need a standard method/tool to document all this information; for this purpose we use UML. UML can be considered as the successor of object-oriented (OO) analysis and design. UML is powerful enough to represent all the concepts that exist in object-oriented analysis and design. UML diagrams are a representation of object-oriented concepts only. Thus, before learning UML, it is essential to understand OO concepts.