In software engineering, structural design patterns are design patterns that ease the design by identifying a simple way to realize relationships among entities. Examples of Structural Patterns include: Adapter pattern: 'adapts' one interface for a class into one that a client expects Adapter pipeline: Use multiple adapters for debugging purposes. Retrofit Interface Pattern: An adapter used as a new interface for multiple classes at the same time. Aggregate pattern: a version of the Composite pattern with methods for aggregation of children Bridge pattern: decouple an abstraction from its implementation so that the two can vary independently Tombstone: An intermediate "lookup" object contains the real location of an object. Composite pattern: a tree structure of objects where every object has the same interface Decorator pattern: add additional functionality to an object at runtime where subclassing would result in an exponential rise of new classes Extensibility pattern: a.k.a. Framework - hide complex code behind a simple interface Facade pattern: create a simplified interface of an existing interface to ease usage for common tasks Flyweight pattern: a large quantity of objects share a common properties object to save space Marker pattern: an empty interface to associate metadata with a class. Pipes and filters: a chain of processes where the output of each process is the input of the next Opaque pointer: a pointer to an undeclared or private type, to hide implementation details Proxy pattern: a class functioning as an interface to another thing See also Behavioral pattern Concurrency pattern Creational pattern References Software design patterns Articles with example Java code Articles with example C Sharp code