what is interface? step by step procedure to use interface .

Interface :

An interface contains only the signatures of methods, delegates or events. It contains only pure virtual methods which required to implement in the derived class that implements the interface.

Interfaces in C # provide a way to achieve runtime polymorphism.


public interface IPayment
{
    void MakePayment(string a, int b=0);
}



public class PayPay : IPayment
{
  public void MakePayment(string a); // it needs only one parameter
}

public class Google : IPayment
{
  public void MakePayment(string a, int b); // it needs two parameters.
}




Interface can be implemented implecitly or explicitly 

http://blogs.msdn.com/b/mhop/archive/2006/12/12/implicit-and-explicit-interface-implementations.aspx