What are abstract classes?

Following are features of a abstract class :

  You cannot create a object of abstract class.

  In VB.NET abstract classes are created using "MustInherit" keyword. In C# we have "abstract" keyword.

  Abstract classes can have implementation or pure abstract methods which should be implemented in the child class.

  Abstract class is designed to act as a base class (to be inherited by other classes). Abstract class is a design concept in program development and provides a base upon which other classes are built.

  Abstract classes are similar to interfaces. After declaring an abstract class, it cannot be instantiated on its own, it must be inherited.