Purpose of Virtual method in C#

When an instance method declaration includes a virtual modifier, that method is said to be a virtual method. When no virtual modifier is present, the method is said to be a non-virtual method.

The implementation of a non-virtual method is invariant: The implementation is the same whether the method is invoked on an instance of the class in which it is declared or an instance of a derived class. In contrast, the implementation of a virtual method can be superseded by derived classes. The process of superseding the implementation of an inherited virtual method is known as overriding that method.

In a virtual method invocation, the run-time type of the instance for which that invocation takes place determines the actual method implementation to invoke. In a non-virtual method invocation, the compile-time type of the instance is the determining factor. In precise terms, when a method named N is invoked with an argument list A on an instance with a compile-time type C and a run-time type R (where R is either C or a class derived from C), the invocation is processed as follows:

• First, overload resolution is applied to C, N, and A, to select a specific method M from the set of methods declared in and inherited by C. This is described in.
• Then, if M is a non-virtual method, M is invoked.
• Otherwise, M is a virtual method, and the most derived implementation of M with respect to R is invoked.

For every virtual method declared in or inherited by a class, there exists a most derived implementation of the method with respect to that class. The most derived implementation of a virtual method M with respect to a class R is determined as follows:

• If R contains the introducing virtual declaration of M, then this is the most derived implementation of M.
• Otherwise, if R contains an override of M, then this is the most derived implementation of M.
• Otherwise, the most derived implementation of M with respect to R is the same as the most derived implementation of M with respect to the direct base class of R.

Kindly have a look into the below class hierarchy

If I am trying to access class “A” information from class “D”, I may receive the error message that, “A” created in ambiguous manner, so we are unable to use this style. Because of that reason only we got a “Virtual” keyword. If we put the keyword in class A and trying to call from “D” class the runtime path will generated directly between the class A and D and we can access through that.

Am I Right? Or wrong?