What are Abstract classes?

Any class with at least one Pure Virtual function is an Abstract class. Abstract classes provide the basic concept of the type, for example Vehicle class can be an Abstract class because in real world there is no instance of Vehicle itself, however there are instances of car, truck etc.

However the class, Vehicle itself defines the basic characteristics and functions of all different types of Vehicles- all the derived classes inherit these characteristics and functions. Each derived class type has its own way in which it could implement the functions and also add its own set of functions that are typical to its behaviour.

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