Virtual & Override:

Virtual & Override: Virtual & Override keywords provides runtime polymorphism. A base class can make some of its methods
as virtual which allows the derived class a chance to override the base class implementation by using override keyword.
For e.g. class Shape
{
int a
public virtual void Display()
{
Console.WriteLine("Shape");
}
}
class Rectangle:Shape
{
public override void Display()
{
Console.WriteLine("Derived");
}
}