There is a common trope within the frontend web development community that boils down to new day, new framework. It is a comment on the velocity at which this profession is changing and evolving. The rapid pace can be exhausting, but it is also exciting because of what it represents. The domain of frontend developers seems to be ever expanding-from simple web pages to web applications, mobile applications, and beyond-and with that, the number of smart people contributing ideas and code to the collective knowledge bank is also expanding.     

With all of that said, any sane person must pick and choose which developments to tune into. When React.js emerged on to the open source scene in May 2013 from the inner-sanctum of Facebook, it would have been easy to brush this library off as just another frontend library. That, however, would have been a mistake. It could be said that React was the most significant and influential open source development in frontend technology in recent memory. Its growth beyond the web and its application in the realm of mobile development through React Native is both a testament to its popularity and a boon to its potential utility.

React Native is a library for creating native mobile applications using familiar web technologies that is built on top of React. What this means is that in order to understand React Native, we must first explore React. In this chapter, we'll examine the fundamentals of React. First, we'll talk briefly about the circumstances that led to React being created. We'll also cover these React concepts: