React is the world's most popular front-end library for building user interfaces. Created and maintained by Facebook as a free-open source tool, React excels in applications where a developer wants to reuse component templates multiple times and in different places. React is an indispensable tool for any JavaScript developer, offering a wide range of frameworks and a vibrant community.

Whenever I need to learn a new technology, step one is to see if there's a video tutorial by the "Net Ninja" Shaun Pelling. His lessons are excellent, easy-to-follow, and will give you all the skills you need to build your first project. If you need to learn to use React this should be your first stop.

Just as react is an essential tool for any front-end JavaScript developer, React Router is an invaluable tool for the React developer. React Router simplifies and strengthens the ability of React to perform URL routing in the front-end, an especially important feature when back-end routing is being used to manage database interactions. React Router should be a part of any React project you make and is built-in to many front-end React frameworks.

React was released in 2013 making heavy use of JavaScript classes. In 2018, a major update introduced Hooks, a faster, simpler, more powerful, and more versatile architecture. Facebook has indicated however that it has no plans to discontinue class-component support so unfortunately many React resources still use them. Your first stop in learning React should be The Net Ninja's React Tutorial series and the second should be this exhaustive article by Eric Bishard.

Gatsby is a framework that supercharges React. It confers the advantages of using a static site generator (SSG) while automating processes like URL routing and content wrapping. It also has a wealth of plugins available, a vibrant support community, and a library of starter sites to quickly stub up a project around. Gatsby was also used to build this website. Learn Gatsby. You'll love it.

If you need to learn to develop apps that function natively in a mobile-device OS environment rather than the browser, React Native is probably the quickest way to learn. If you already know React you're halfway there and if you don't know React yet, you should. A single codebase will allow your apps to run in both OS environments.