The reason react is so popular is that it is really fast, because its built on Virtual DOM which is faster than the real DOM. Any changes that happen on virtual dom are rendered faster by the browser.

An application that reacts promptly leads to a great User Experience. The javascript library lives up to its name, its called REACT because it is fast and it definitely creates an engaging user experience.

There are components and sub-components in React. Components help UI developers to break down complex code into simpler manageable entities. Developing in React is faster and scalable.

Because REACT JS came from a tech giant, it quickly developed a big community and fan base, a whole repository of libraries are available to further extend react. When any language has an active community, its easy to switch vendors because the support for it is widespread.

React Native is a framework for building native apps using React JS. This means that components used in web applications can be ported directly to your native mobile applications. This solves a big problem for developers who had to maintain separate code base for website, android and ios applications.

React works on downward data flow. This ensures that children work independently of parents, a code change in children components do not affect parent components.