While developing a software solution, various discussions take place to plan and determine the best possible procedure for the product development process.

In this process, different developers would have different opinions and might be unable to come up with a commonly accepted approach to solve a specified problem.

This diversity can lead to different variations in source code that can make the software difficult to distribute, extend, reuse, and manage by fellow developers. Hence, there is a need for standardization in the case of object-oriented software.

This problem of standardization was solved with the introduction of Design Patterns in 1995 in the Design Patterns: Elements of Reusable Object-Oriented Software book (also called the Gang of Four) which was written by Erich Gamma, John Vlissides, Ralph Johnson, and Richard Helm.

Design patterns are a toolkit of tried and well-tested solutions to common software design problems created by experienced object-oriented practitioners. As a result, the design patterns are considered a standard in object-oriented software design i.e., if you want to build an object-oriented software using best practices, then you should follow the Software Design Patterns.

Types Of Design Patterns

Design patterns are mainly classified into 3 categories

Creational Patterns

The traditional method of object creation can lead to the instantiation of objects in an uncontrolled fashion.

It can scatter objects all over the application which can increase the overall application design complexity. This can make an object-oriented application unstable and can lead to design problems. Creational Design Patterns reduce this design instability and complexity by providing different ways to implement controlled object creation in an object-oriented application.

There are 5 different creational design patterns, namely : - Singleton pattern - Factory pattern - Abstract Factory pattern - Builder pattern - Prototype pattern

Structural Patterns

Structural Design Patterns provide different ways to organize the classes and objects in an object-oriented application such that it leads to simplification of the design of large and complex structures.

It describes the process using which we can combine classes and objects to form an organized, flexible, and connected structure. There are 7 different types of structural design patterns. These include : - Adapter pattern - Composite pattern - Proxy pattern - Fly Weight pattern - Facade pattern - Bridge pattern - Decorator pattern

Behavioral Patterns

Behavioral design patterns deal with the interaction of objects with each other. These patterns follow the fact that the objects in an object-oriented application should be interconnected in such a way that hard coding can be avoided and the user input can be well handled.

These design patterns make use of loose coupling techniques to ensure a flexible and effective flow of information. Behavioral design patterns include 12 different patterns namely : - Chain of Responsibility Pattern - Command Pattern - Interpreter Pattern - Iterator Pattern - Mediator Pattern - Memento Pattern - Observer Pattern - State Pattern - Strategy Pattern - Template Pattern - Visitor Pattern - Null Object Pattern