React is a JavaScript library for building user interfaces. It was created by Facebook (now Meta) in 2013 and is the most widely used frontend library in the world.
Without a library like React, building a web interface means manually telling the browser what to change when something happens — "when the user clicks this button, find this element, update its text, add this class, remove that one." For anything beyond a static page, this gets tedious fast.
React flips the model. You describe what the screen should look like for a given state, and React figures out what to change. Click a button to add an item? You just update the list — React handles adding the new element to the page.
React didn't become dominant by accident. A few things set it apart:
Components. Everything is a reusable piece. A button, a card, a whole page — they're all components you can compose like building blocks. Build a card once, use it ten times with different content.
Massive ecosystem. Because React has been around for over a decade and is used by millions of developers, there's a library for almost anything you'd want to do — forms, animations, charts, authentication, drag-and-drop. Whatever your AI suggests, there's probably a React library for it.
AI knows it best. This is the practical reason that matters most for you. AI coding tools have been trained on more React code than any other frontend library. When you ask your AI to build a feature, it will write better, more reliable React code than it would for any alternative — because it's seen more examples of how React should work.
Vue, Svelte, and Angular are all solid choices. Vue is approachable, Svelte compiles away the framework overhead, and Angular is a full-featured platform for large teams.
But each one has a smaller ecosystem, fewer learning resources, and less AI training data. If you were a professional developer choosing based on technical preference, any of these could work. Since you're building with AI, the size of the ecosystem matters more than the technical differences — and React's ecosystem is the largest by far.
One thing worth knowing: React only handles what the user sees and interacts with. It doesn't handle routing (navigating between pages), data loading, or server-side logic. That's where a framework like React Router comes in — it builds on top of React to handle the full picture.
?Why React Router?