React JS is a popular open-source JavaScript library used for building user interfaces, particularly for single-page applications. Developed by Facebook, React allows developers to create large web applications that can update and render efficiently in response to changing data without reloading the page. It uses components, which are reusable pieces of code, to build the user interface in a modular way. React is known for its speed, simplicity, and scalability, making it a favorite choice for front-end developers.

Prerequisites

We’ll assume that you have some familiarity with HTML and JavaScript, but you should be able to follow along even if you’re coming from a different programming language. We’ll also assume that you’re familiar with programming concepts like functions, objects, arrays, and to a lesser extent, classes.