Design Patterns

Some useful definitions of design patterns are:

Desingn patterns constitute a set of rules describing how to accomplish certain tasks in the realm of software development.

Design patterns focus more on reuse of recurring architectural design themes while frameworks focus on detailed design and implementation.

A pattern addresses a recurring design problem that arises in specific design situations and presents a solution to it.

Patterns identify and specify abstractions that are above the level of single classes and instances, or of components.