Still Confusing!!

An interface is like a class, except that (for current purposes) it only has abstract methods. If a class you write implements an interface, then it must make those abstract methods concrete, i.e., you must write code blocks for them. Why have them? One of the standard answers is that with interfaces you can have polymorphism without inheritance! Another is that by having your class implement an interface the compiler will make sure you do override those abstract methods. I.e., it will enforce the contract the interface represents. Another answer is that it is a way to have something like multiple inheritance without the problems of multiple inheritance. And there are other answers as well.

An Interface is like minimum requirements for a class. If a class implements an interface it should implement or override all of the methods from the interface.