26/05/2026
What is React.js?
React is an open-source JavaScript library developed by Meta (Facebook) for building user interfaces, specifically for single-page applications (SPAs).
It focuses purely on the view layer of an application—meaning it gives you the tools to build reusable UI components (like buttons, forms, and navigation bars), but leaves everything else (routing, data fetching, build tools) up to you to figure out.
How it works: By default, React uses Client-Side Rendering (CSR). When a user visits a React site, a blank HTML sheet and a large JavaScript file are sent to the browser. The browser then executes the JavaScript to construct and display the page.
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What is Next.js?
Next.js is a React framework created by Vercel. It takes the core power of React and adds production-ready features right out of the box.
Instead of forcing you to manually pick, install, and configure libraries for routing, optimization, and server handling, Next.js provides a structured, opinionated setup where these features are built-in.
How it works: Next.js supports Server-Side Rendering (SSR) and Static Site Generation (SSG). Instead of making the browser do all the heavy lifting, Next.js can pre-render the HTML pages on the server and send a fully formed page to the user's browser instantly.