Interface: An interface is like a class with nothing but abstract methods. All methods of an interface must be public. It is also possible to declare a constructor in an interface. It’s possible for interface to have constants(can not be overridden by a class/interface that inherits them). interface keyword is used to create an interface in php. Interface don’t have instance variables. All methods of an interface is abstract. All methods of an interface are automatically (by default) public. We