I start the study of design patterns with a pattern that you have probably implemented in the past but may not have had a name for: the Facade pattern.
• Explains what the Facade pattern is and where it is used.
• Presents the key features of the pattern.
• Presents some variations on the Facade pattern.
• Relates the Facade pattern to the CAD/CAM problem.
According to the Gang of Four, the intent of the Facade pattern is to
Provide a unified interface to a set of interfaces in a subsystem. Facade defines a higher-level interface that makes the subsystem easier to use.1