PHP Tutorial for Beginners | PHP OOP Interface Examples

You will often hear that an interface is a contract. This is true in as much as an interface defines the public methods that a class must implement. For example, if you have two objects that are each instance of a different class, yet they implement the same interface, then both objects must at a minimum offer the public methods defined in the interface which they implement. An interface contains no logic. In addition to this, interfaces contain no data variables, only function prototypes.