Class a Abstract Data Type: is a template for creating objects. A class describes a collection of related objects i.e. instances of the classes. Basically classes are user-defined data types and behave like the built-in types of a programming language. The syntax used to create an object is no different than the syntax used to create an integer object in C. If student has been defined as a class, then the statement below will create an object mercy belonging to the class student. 

student mercy; 

A class description include definitions of 

•  Operations of the objects of the class 

•  Possible set of states