Decouple an abstraction from its implementation allowing the two to vary independently.

Attach additional responsibilities to an object dynamically keeping the same interface. Decorators provide a flexible alternative to subclassing for extending f...

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.

Use sharing to support large numbers of similar objects efficiently.

Provide a surrogate or placeholder for another object to control access to it.

Provide an interface for creating families of related or dependent objects without specifying their concrete classes.

Separate the construction of a complex object from its representation allowing the same construction process to create various representations.

Without violating encapsulation, capture and externalize an object’s internal state allowing the object to be restored to this state later.

Allow an object to alter its behavior when its internal state changes. The object will appear to change its class.

Compose objects into tree structures to represent part-whole hierarchies. Composite lets clients treat individual objects and compositions of objects uniformly.