What does interface mean in OOP?

In general, an interface is a device or a system that unrelated entities use to interact .

Interfaces allow you to specify what methods a class should implement . Interfaces make it easy to use a variety of different classes in the same way. When one or more classes use the same interface, it is referred to as “polymorphism”.

Why do we use an Interface? It is used to achieve total abstraction . Since java does not support multiple inheritances in the case of class, by using an interface it can achieve multiple inheritances. It is also used to achieve loose coupling.