Object-Oriented Analysis and Design is the collection of approaches and processes used to develop a software system that has an object as its base structure. The concept of an object in this regard can be thought of like a cell being the base structure of all life. When you focus on the creation of objects that when implemented together in various combinations creates the functionality of your system, then you have an object-oriented system. This is not to be confused with an object-based system which uses objects and classes, but only to the extent that the constructs hold data to be used by the system. In an OO system the objects, more specifically the business objects, contain the brains of the business.