We have learned a lot about polymorphism and Inheritance. In this article of the series “Diving Into OOP”, we'll discuss the hottest and most exciting topic of OOP in C#, Abstract Classes. The concept of Abstract classes is the same for any other language, but in C# we deal with it in a bit of a different way. Abstract classes play a different and very interesting role in polymorphism and inheritance. We'll cover all the aspects of abstract classes with our hands-on lab and theory as an explanation to what output we get. We'll also list the points to remember at the end of the article.