What is the Facade pattern and what problem does it solve?

Explanation

The Facade pattern provides a simplified, unified interface to a set of interfaces in a subsystem. It defines a higher-level interface that makes the subsystem easier to use by hiding its complexity. Facade does not encapsulate the subsystem (components remain accessible); it merely provides a convenience layer. Use Facade when: a subsystem is complex, you want to layer your system, or you want to provide a limited API for clients. Examples include API gateways, service wrappers, and simplified SDK interfaces over complex libraries.