Interfaces can inherit from one or more interfaces. The derived interface inherits the members from its base interfaces. A class that implements a derived interface must implement all members in the derived interface, including all members of the derived interface's base interfaces.

Are interfaces inheritance or composition?

An alternative to inheritance in OOP is using interfaces and composition in object-oriented programming. Interfaces have long been used as an alternative to multiple inheritance, even if inheritance is actively used in a class hierarchy.

What is interface inheritance?

An interface contains variables and methods like a class but the methods in an interface are abstract by default unlike a class. Multiple inheritance by interface occurs if a class implements multiple interfaces or also if an interface itself extends multiple interfaces.