This post can be used as a quick refresher of the GoF Structural Design Patterns. I have just given the intents of each of the structural patterns. This will be of use to experienced professionals.
INTENT: Convert the interface of a class into another interface that clients expect. Adapter lets classes work together that couldn’t otherwise because of incompatible interface.
INTENT: Decouple an abstraction from its implementation so that the two can vary independently.
INTENT: Compose objects into tree structures to represent part-whole hierarchies. Composite lets clients treat individual objects and compositions of objects uniformly.
INTENT: Attach flexible additional responsibilities to an object dynamically. Decorators provide a flexible alternative to subclassing for extending functionality.
INTENT: 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.
INTENT: Use sharing to support large numbers of fine-grained objects efficiently.
INTENT: Provide a surrogate or placeholder for another object to control access to it.