In this chapter, we have discussed major design patterns used in modern software development that were introduced in the previous chapter. We started with the discussion of various software development principles such as the DRY, KISS, YAGNI, MVP, and SOLID programming principles. Then, we covered software development patterns including GoF and EIPs. The methodology for SDLC was covered, including Waterfall and Agile. The purpose of this chapter was to illustrate how patterns are used across all levels of software development. 

As the software industry matures, patterns emerge as experience evolves, techniques grow, and technology advances. Some patterns have been developed to help different phases of the SDLC. For example in Chapter 3, Implementing Design Patterns - Basics Part 1, Test-driven development (TDD) will be explored, where the definitions of tests are used to provide both measurable progress as well as clear requirements, during the development phase. As the chapters progress, we will discuss higher levels of abstraction in software development, including patterns for web development as well as modern architecture patterns for on-premise and cloud-based solutions. 

In the next chapter, we will start by building a fictitious application in .NET Core. Also, we will explain the various patterns discussed in this chapter, including programming principles such as SOLID, and illustrate several GoF patterns.