The term “Design Pattern” in software engineering refers to a known arrangement of software components that solves a particular problem. These structures provide both a known terminology and known implementation such that once the particular problem is identified, the known structure can be applied. One of the earliest formal definitions of software patterns is detailed in Design Patterns: Elements of Reusable Object-Oriented Software (Gamma et al., 1994), sometimes referred to as the “Gang of Four” (GoF) because of the four original authors. That work has been the inspiration for several updated and language-specific books. In this section we will briefly cover a few GoF patterns to demonstrate the terminology and as an introduction to thinking in patterns. We will then talk about some of the more prevalent patterns in use today in the highly distributed world. Finally we will cover some architectural patterns that are common in large distributed systems and hardware farms that are built for performance and resiliency.