Introducing the Facade Pattern
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
Intent: A unified, high-level interface
Basically, this is saying that we need to interact with a system that is easier than the current method, or we need to use the system in a particular way (such as using a 3D drawing program in a 2D way). We can build such a method of interaction because we only need to use a subset of the system in question.