A design pattern is an attempt to fulfill reoccuring design requirements by reusing solutions which have been solved time and time again. In fact, one could almost look upon design patterns as a standard arsenal that every programmer should have in his skill set.

Although the concept is not exactly new in it basic form - reusing stable code has been the skill of many programmer, design patterns attempt to essentially standardize the pratice for common challenges.

Design patterns are broken down into groups according to the type of general problem they solve.

 

Pattern	Summary	Examples
Behavioral Patterns	allow communication between objects	state, command
Creational Patterns	object creation	singleton, class factories
Concurrency Patterns	solve concurrency issues, locking	thread pool, io
Fundamental Patterns	patterns general in nature	interface, delegate
Structural Patterns	create relationships between objects	bridge, proxy