Mediator pattern and coupling

The mediator pattern in a behavioral pattern unlike structural patterns such as facade and adaptor.

Mediator Pattern: In layman's terms a mediator is a person who acts as a point of reference between parties. In the same sense a mediator class is one that acts as a point of reference between two classes that depend on each other. In an environment where the requirements and the system design is continuously changing such a design pattern is used.

Introducing a mediator reduces the coupling between the classes thus making maintenance of the application relative easy.