what is the concept of interface? and what is use of it?

Question

please give me with examples

Answer 1

It's some kind of contract. Interface includes methods signatures and force classes implementing this interface to implement all methods which are declared in the interface.

Answer 2

interface ICreature
{
void speak();
void drink();
bool isAlive();
}

public class Human : ICreature
{
public void speak()
{
//implementation
}

public void drink()
{
//implementation
}

public bool isAlive()
{
//implementation
}
}