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Software professionals may be familiar with the term “Design Patterns” but many have no idea of where they come from and what they truly are. Design patterns are commonly defined as time-tested solutions to recurring design problems. Design patterns are represented as relationships between classes and objects with defined responsibilities that act in concert to carry out the solution. Design patterns have two major benefits. First, they provide us with a way to solve issues related to software development using a proven solution. The solution facilitates the development of highly cohesive modules with minimal coupling. They isolate the variability that may exist in the system requirements, making the overall system easier to understand and maintain. Second, design patterns make communication between designers more efficient. Software professionals can immediately picture the high-level design in their heads when they refer the name of the pattern used to solve a particular issue when discussing system design.

Design Patterns originally grouped design patterns into the categories Creational Patterns, Structural Patterns, and Behavioral Patterns, and described them using the concepts of delegation,aggregation, and consultation.

Head First Design Patterns is one of the best one about design pattern analysis.