Overview: In this tutorial, we will explain what design patterns are and how they are useful. This tutorial will describe several design patterns in detail, giving a simple example in Java for each. We will also look at a plug-in for Eclipse that helps create design patterns. About Design Patterns: After programming several projects using object orientation, you may find that you are programming similar structures again and again. In the book Design Patterns by Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides, the authors describe 23 design patterns that they have found to be recurring in object orientated programming. The four authors of Design Patterns are nicknamed the Gang of Four (GoF) and the design patterns in the book are considered to be GoF design patterns. Design patterns are an aid in programming in that they allow programmers to reuse a lot of code and structure instead of having to continually recode similar designs. This leads to faster development and higher-quality code.