Next.js is an open-source web development framework built on top of Node.js enabling React-based web applications functionalities such as server-side rendering and generating static websites. React documentation mentions Next.js among "Recommended Toolchains" advising it to developers as a solution when "Building a server-rendered website with Node.js". Where traditional React apps can only render their content in the client-side browser, Next.js extends this functionality to include applications rendered on the server-side.
Next.js supports styling with CSS as well as precompiled Scss and Sass, CSS-in-JS, and styled JSX. In addition, it is built with TypeScript support and smart bundling. Next.js also supports Incremental Static Regeneration (ISR) and static site generation (SSG) - A compiled version of the website is usually built during build time and saved as a .next folder.