What is React?

React is a JavaScript library for building user interfaces. It was created by Facebook (now Meta) and released as open source in 2013. It became massively popular in the mid-2010s and is now one of the most widely used front-end libraries, used by companies like Facebook, Instagram, Netflix, Airbnb, and thousands of others.

React’s big idea is that you build your UI out of reusable components. The main breakthrough for rendering and re-rendering is the virtual DOM. Instead of manually updating the page when data changes, React creates a lightweight copy of the DOM in memory, figures out what changed, and efficiently updates only the parts of the actual page that need to change.

Here’s a simple example of a React component:

function WelcomeMessage({ name }) {
  return <h1>Hello, {name}!</h1>;
}

That HTML-looking syntax is called JSX. It’s not actually HTML, it gets transformed into JavaScript that React can work with. JSX is one of the most HTML-like templating languages out there. Other front-end frameworks use templating languages with {{ }} style tags that feel less natural. JSX lets you mix code and markup together, keeping related things in one place where they’re easier to understand.

React works great for building SPAs (Single Page Applications) where you want a smooth, app-like experience in the browser. But it’s also been adapted for other platforms. React Native lets you build mobile apps for iOS and Android using React. And frameworks like Next.js and Remix extend React with server-side rendering and other features. The ecosystem is huge, with tons of libraries and tools built around React.

The learning curve can be steep at first, especially if you’re new to modern JavaScript. You need to understand concepts like components, props, state, hooks, and the component lifecycle. But once it clicks, React makes it much easier to build and maintain complex interactive UIs.

There are many other popular front-end frameworks like Vue, Svelte, and Angular. Many developers dislike certain aspects of React and prefer these alternatives. Each framework has its own philosophy and trade-offs. But as of 2026, React is still clearly on top in terms of adoption and job market demand.

I’ve been using React professionally since it came out. I was a somewhat early adopter and got to see the evolution firsthand. At my current job, I’m primarily a React developer. The component model makes it easy to break down complex UIs into manageable pieces. And the ecosystem is massive, so there’s usually a library or solution for whatever you need to build.