What is an interface in the context of PHP OOP?

In PHP OOP, an interface is indeed a contract or a set of rules that defines a specific behavior or functionality. It provides a way to establish a common structure and ensure that classes that implement the interface adhere to that structure. An interface contains only method signatures without implementation. Classes that implement an interface must provide an implementation for all the methods defined in the interface. Interfaces allow for polymorphism and provide a way to define a common interface that multiple classes can adhere to. For further information, visit: http://php.net/manual/en/language.oop5.interfaces.php