What is an Abstract Class / Abstract Classes in C#

Abstract classes are the ones that do not require instantiation. Abstract classes should never be instantiated, it is important to correctly define their constructors. It is also important to ensure that the functionality of your abstract class is correct and easily extended

Abstract (MustInherit in Visual Basic) classes can behave like interfaces or regular classes in that they can define members, and they can provide implementation details but are not required to do so. If an abstract class does not provide implementation details, concrete classes that inherit from the abstract class are required to provide the implementation.

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