You can use interfaces to describe which methods a class should implement. Interfaces make it simple to use multiple classes at the same time. The term "polymorphism" refers to when two or more classes share the same interface.
An interface defines the set of methods (or messages) that an instance of a class with that interface can respond to in object-oriented programming.
The interface keyword is used to declare an interface. Its purpose is to provide complete abstraction. By default, all fields are public, static, and final, and all methods in an interface are declared with an empty body and are public.