Chapter 1, Everything You Should Know About React, introduces you to the base concepts of React, seen from an advanced perspective.

Chapter 2, Clean Up Your Code, teaches that one of the most important aspects of writing maintainable code is to keep it clean and follow a coding style guide. To use React, it is also important to know the basics of functional programming.

Chapter 3, Create Truly Reusable Components, informs that building an application using components is a key factor, but creating truly reusable components is the most important thing to do in order to keep the codebase clean and maintainable.

Chapter 4, Compose All the Things, says that real applications are created using different components and it's important to make them communicate effectively, organizing and structuring the hierarchy in the right way.

Chapter 5, Proper Data Fetching, instructs that any client-side application has to deal with data at some point; it takes you through the different techniques and approaches that can be used to fetch data in the React-way.

Chapter 6, Write Code for the Browser, states that our applications live in the browser and we should know how to use it properly. This chapter will go through some advanced concepts, such as events, animations, and how to interact with the DOM.

Chapter 7, Make Your Components Look Beautiful , demonstrates that crafting beautiful UI components is a big part of the frontend engineering work. With React, there are different ways of doing it and each one tackles the problem from a different perspective. It's important to know which libraries are available and how they work in order to choose the right one.

Chapter 8, Server-Side Rendering for Fun and Profit, instructs that one of the greatest features of React is the server-side rendering. It works out of the box, but it's important to learn how to use it in the right way to get the most out of it.

Chapter 9, Improve the Performance of Your Applications, informs that on the Web, performance is one of the most important factors to engage users. React offers a set of tools and techniques to create lightning-fast applications, and this chapter goes through all of them.

Chapter 10,  About Testing and Debugging, makes you realize that we all want our applications to be stable and handle all the edge cases: tests help with that. Writing a comprehensive set of tests is vital to creating rock-solid and maintainable code. On the other hand, bugs always happen and it's crucial to know how to debug and find an issue as early as possible.

Chapter 11,  Anti-Patterns to Be Avoided, explains the fact that developers often try to use shortcuts and creative solutions, but in some cases these workarounds can be dangerous for their applications, especially with big teams and large codebases. This chapter takes you through the common anti-patterns to be avoided while using React.

Chapter 12, Next Steps, is the last chapter, and all the topics have been covered. I believe it's important to mention how to open source components (to give back to the community) and how to contribute to React and its ecosystem.