The primary motivation of using classes in a program is to create objects as complete as possible. An object must be able to handle its own business so that the other objects of the program or of another program would only need to know which object can take care of a particular need they have. A regular variable, as a member of an object, cannot handle assignments. This job is handled by particular functions declared as members of a class. A function as a member of a class is also called a Method. On this site, the words "method" and "function", when associated with a class, will refer to the same thing: a member function of the class.