Abstract Factory Pattern

The Abstract Factory Pattern provides an interface for creating families of related or dependent objects without specifying their concrete classes.

This pattern saves clients the bother of instantiating families of products. The client is written against an abstract factory interface. The interface, which creates products in the abstract, is implemented in concrete factories which create the particular families of products from concrete implementations of abstract product classes.

One question I have is whether the client needs to also be written against the abstract product classes, as the Wikipedia article on this pattern suggests.