The React library has created a new way to develop user interfaces for web applications through creating declarative and composable components in the new, but familiar, JSX syntax. Since its introduction, it has grown immensely in popularity. At Facebook's F8 developer conference in 2016, it was estimated that upwards of 250,000 developers were using React in some way. This enthusiasm led the community to look for new places to use their favorite library, and in early 2015, React Native was born.

In this chapter, we covered the fundamentals of React, from conception to implementation. We learned how to take a user interface and structure it as components, the building blocks of React applications. Starting with simple components, such as a static title, we then built up to more complex components by adding props, event handlers, state, and lifecycle methods. Finally, we looked at some alternate ways of representing React components and discussed when each was appropriate.

In the next chapter, we will take this knowledge of React into the realm of native mobile applications by building a Hello World application in React Native.