Abstract class – Defines the methods and common attributes of a set of classes that are conceptually similar.  Abstract classes are never instantiated.

Attribute - Data associated with an object (also called a data member.)

Class – Blueprint of an object - defines the methods and data of an object of its type.

Constructor - Procedure that is invoked when an object is created.

Concrete class – A class that implements a particular type of behavior for an abstract class. Concrete classes are specific, non-changing implementations of a concept.

Derived Class - A class that is specialized from a base class.  Contains all of the attributes and methods of the base class but may also contain other attributes or different method implimentations.

Destructor - Procedure that is invoked when a object is deleted.

Encapsulation – Typically defined as data hiding, but better thought of as any kind of hiding (type, implementation, design, and so on.) Objects encapsulate their data.  Abstract classes encapsulate their derived concrete classes.

Functional Decomposition - A method of analysis in which a problem is broken into smaller and smaller functions.

Inheritance – A way that a class is specialized, used to relate derived classes with their base classes. A class inherits from another class when it receives some or all of the qualities of that class.  The starting class is called the base, super, parent, or generalized class, whereas the inheriting class is called the derived, sub, child, or specialized class.

Instance – A particular example of a class. (It is always an object.) A particular instance or entity of a class.  Each object has its own state.  This enables me to have several objects of the same type (class).

Instantiation – The process of creating an instance of a class.

Interface – An interface is like a class, but only provides a specification – and not an implementation – for its members.  It is similar to an abstract class consisting only of abstract members.  When programming, you use interfaces when you need several classes to share some characteristics that are not present in a common base class and want to be sure that each class implements the characteristic on its own (because each member is abstract.)

Member - Either data ora procedure of a class.

Method - Procedures that are associated with a class.

Object - An entity with responsibilities.  A special, self-contained holder of both data and procedures that operate on that data.  An object's data is protected from external objects.

Perspectives – There are three different perspectives for looking at objects: conceptual, specification, and implementation.  These distinctions are helpful in understanding the relationship between abstract classes and their derivations.  The abstract class defines how to solve things conceptually.  It also gives the specification for communicating with any object derived from it. Each derivation provides the specific implementation needed.

Polymorphism – Being able to refer to different derivations of a class in the same way, but getting the behavior appropriate to the derived class being referred to.

Superclass - A class from which other classes are derived. Contains the master definitions of data nad procedures that all derived classes will use (and for procedures, possibly override.)