An interface in PHP OOP is a contract that specifies what methods a class must implement.

An interface in PHP OOP is indeed a contract that specifies what methods a class must implement. It establishes a set of rules or a contract that a class must adhere to when implementing the interface. The interface defines the method signatures that the implementing class must provide an implementation for. By implementing the interface, the class ensures that it fulfills the requirements and guarantees the expected behavior. Interfaces allow for polymorphism and provide a way to define a common interface that multiple classes can adhere to. To learn more, visit: http://php.net/manual/en/language.oop5.interfaces.php