Why do we use virtual and override?

Question

Why do we use override and virtual if it gives the same effect when we dont use override and virtual?

example 1:

class BaseClass
{
    public virtual         


        

Answer 1

(note, I'm quietly ignoring the compile errors)

Now do:

BaseClass obj = new DerivedClass();
Console.WriteLine(obj.call());

Without virtual, this will print A, when actually a DerivedClass should be writing B. This is because it has simply called the BaseClass implementation (since obj is typed as BaseClass, and no polymorphism is defined).