Cat, Dog and Mouse are all classes that implement the Animal interface, which means that all of them are able to make a sound using the makeSound() method. Because of this, we can loop through all of the animals and tell them to make a sound even if we don't know what type of animal each one is. Since the interface does not tell the classes how to implement the method, each animal can make a sound in its own way.

Meow Bark Squeak