Like structured design, the term object-oriented design (OOD) means di — Edward V. Berard

"Objects are the real and conceptual things we find in the world around us. An object may be hardware, software, a concept (e.g., velocity), or even "flesh and blood." Objects are complete entities, i.e., they are not "simply information" or "simply information and actions." Software objects strive to capture as completely as possible the characteristics of the "real world" objects which they represent. Finally, objects are "black boxes," i.e., their internal implementations are hidden from the outside world, and all interactions with an object take place via a well-defined interface."

"Object-oriented domain analysis seeks to identify reusable items localized around objects e.g., classes, instances, systems of interacting objects, and kits."

"An object which is used to create instances, i.e., a template, description, pattern, or "blueprint" of a category or collection of very similar items. Among other things, a class describes the interface the these items will present to the outside world, i.e., the available and appropriate methods, constants, and exceptions. A class represents an abstraction of the items. A class may itself be parameterized (i.e., it actually represents a family of very closely related classes), in which case we refer to it as a parameterized class. Class is a recursive concept. Specifically, we may define classes as being composed of other classes (i.e., heterogeneous composite classes and homogeneous composite classes), in terms of itself (a recursively defined class), as inheriting characteristics from one or more other classes (i.e., the superclasses of the class), and as providing characteristics to other classes (i.e., the subclasses of the class). In some places, classes are defined as "the set of all instances of a type," and the term "type" is given the above definition for class."

"An action which is suffered by, or required of, an object. Operations may be selectors, constructors, or iterators. An operation is contained in an objects interface and has its details described in a corresponding method. Operations may be composite, i.e., composed of other operations. However, encapsulation of composite operations within the interface to an object is not encouraged."

"Walking on water and developing software from a specification are easy if both are frozen."

"Recently, I have had conversations with a number of people who were attempting their first object-oriented project. Most of these people claimed to be using “use cases” in their object-oriented analysis and design approaches. However, listening to them describe their projects, it became quite apparent to me that there is a great deal of confusion regarding the definition, context, and use of use cases. This confusion can (and often does) lead to poorly-designed systems."