What are the differences between Next js and React js ?

Next.js and React.js are both popular JavaScript frameworks used for building web applications, but they serve different purposes and have distinct features:

1. Purpose:

   • React.js: React.js is a JavaScript library developed by Facebook for building user interfaces, specifically for creating dynamic and interactive UI components.
   • Next.js: Next.js is a React framework that provides additional features for building server-side rendered (SSR) React applications, static websites, and hybrid applications.

2. Routing:

   • React.js: React.js does not provide built-in routing capabilities. Developers typically use third-party libraries like React Router for managing routing in React applications.
   • Next.js: Next.js includes built-in routing capabilities, making it easier to handle client-side routing without needing additional libraries.

3. Server-side rendering (SSR) and Static Site Generation (SSG):

   • React.js: React.js primarily focuses on client-side rendering (CSR), where the rendering process occurs in the user's browser.
   • Next.js: Next.js supports both server-side rendering (SSR) and static site generation (SSG). SSR renders React components on the server before sending HTML to the client, while SSG generates static HTML files at build time.

4. File-based routing:

   • React.js: React.js projects typically require developers to set up routing manually using libraries like React Router and define routes explicitly.
   • Next.js: Next.js uses a file-based routing system where routes are automatically generated based on the file structure of the pages directory. This simplifies the routing process and makes it more intuitive.

5. API Routes:

   • React.js: React.js does not provide built-in support for defining API routes.
   • Next.js: Next.js allows developers to create API routes within their Next.js applications, making it easy to implement server-side logic and interact with databases or external services.

6. Static Site Generation (SSG):

   • React.js: React.js does not provide built-in support for static site generation.
   • Next.js: Next.js allows developers to generate static websites at build time, enabling faster page loads and improved SEO performance.

In summary, React.js is a JavaScript library for building UI components, while Next.js is a framework built on top of React.js that adds features like server-side rendering, file-based routing, API routes, and static site generation, making it suitable for a wider range of web applications and projects.