An interface in Java describes a set of methods that can be called on an object.

Interfaces offer a capability requiring that unrelated classes implement a set of common methods.

Interfaces may not specify any implementation details, such as concrete method declarations and instance variables.

An interface declaration begins with the keyword interface and contains only instance variables and protected methods.

Interfaces define and standardize the ways in which things such as people and systems can interact with one another.

All interface members must be public.