What is React?

React is a JavaScript library, made by Meta, for building user interfaces. Instead of writing one big HTML page, you build your UI out of components: small, reusable functions that return what should appear on screen.

function Welcome() {
  return <h1>Hello, React!</h1>;
}

Why React?

• Components: build a button once and reuse it everywhere.
• Declarative: you describe what the UI should look like for the current data, and React updates the page for you.
• Fast updates: React changes only the parts of the page that actually changed.
• Huge ecosystem: routing, forms, animation, charts: there's a library for everything.
• Jobs: React is the most requested frontend skill in job listings.