What is an Abstract Class in C#?

•  An Abstract class is a class which is denoted by abstract keyword and can be used only as a Base class. An Abstract class should always be inherited. An instance of the class itself cannot be created. If we do not want any program to create an object of a class, then such classes can be made abstract.
• Any method in the abstract class does not have implementations in the same class. But they must be implemented in the child class.

EX :    abstract class AB1{

          Public void Add();

          }

          Class childClass : AB1

         {

         childClass cs = new childClass ();

        int Sum = cs.Add();

          }