Analogy
Before Next.js, building a web application was like assembling a car from individual parts. It was a complex and time-consuming process that required deep knowledge of each component. Next.js, on the other hand, is like buying a pre-assembled car. It comes with everything you need, pre-configured and ready to go. This not only saves you time and effort but also ensures that the final product is well-built and optimized.

Let's understand how it was before React and what changed after Next.js

Before Next.js: The React Landscape
Before Next.js, React developers faced a number of challenges when building web applications. While React provided a powerful component-based approach to building user interfaces, it left many crucial aspects of web development up to developers to implement themselves.

1. Routing

Manual Implementation: Developers had to manually create and manage routing logic using libraries like React Router, which often involved complex configuration and state management.
Limited Features: These libraries, while functional, lacked the advanced features and optimizations offered by Next.js's built-in router.

2. Rendering

Client-Side Rendering (CSR): All rendering was done on the client-side, which could lead to slower initial page loads, especially for complex applications.
Server-Side Rendering (SSR): SSR was possible but required significant manual setup and could be challenging to maintain.
No Static Rendering: There was no built-in support for statically generating pages, which can significantly improve performance and SEO.

3. Data Fetching

Manual Data Fetching: Developers had to manually fetch data using libraries like Axios or fetch, which often involved complex state management and error handling.
Lack of Optimization: There were no built-in mechanisms for data caching, revalidation, or request memoization.

4. Styling

Limited Support: While React supported CSS, there were no built-in solutions for CSS Modules, Tailwind CSS, or CSS-in-JS.
Manual Management: Developers had to manually manage styling and handle conflicts between different stylesheets.

5. Performance Optimization

Manual Optimization: Developers had to manually optimize images, fonts, and scripts to improve performance and Core Web Vitals.
Lack of Tools: There were no built-in tools to help with these optimizations.

6. TypeScript Support

Limited Support: While TypeScript could be used with React, there were limitations in terms of type checking and compilation speed.
Manual Setup: Developers had to manually set up TypeScript and configure it for their projects.

Next.js: A Game-Changer

Next.js addressed many of these challenges by providing a comprehensive framework built on top of React. It introduced several key improvements:

1. Simplified Routing

File-System-Based Routing: Next.js automatically generates routes based on the structure of your project's files, making routing much simpler and more intuitive.
Advanced Features: It supports layouts, nested routing, loading states, error handling, and other advanced routing features.

2. Optimized Rendering

Server-Side Rendering: Next.js makes it easy to render pages on the server, improving initial page load times and SEO.
Static Rendering: It also supports statically generating pages, which can further enhance performance and reduce server load.
Edge and Node.js Runtime Support: Next.js can be deployed to edge networks for even faster performance.

3. Simplified Data Fetching

Async/Await in Server Components: Data fetching is made easier with the use of async/await in Server Components.
Extended Fetch API: Next.js provides an extended fetch API with features like request memoization, data caching, and revalidation.

4. Improved Styling

Built-in Support: Next.js supports popular styling methods like CSS Modules, Tailwind CSS, and CSS-in-JS.
Automatic CSS Extraction: It automatically extracts CSS from your components, making styling management easier.

5. Enhanced Performance Optimization

Built-in Optimizations: Next.js includes built-in optimizations for images, fonts, and scripts, helping to improve your application's Core Web Vitals.
Automatic Code Splitting: It automatically splits your code into smaller bundles, reducing initial load times.

6. Better TypeScript Support

Improved Type Checking: Next.js provides better type checking and more efficient compilation, thanks to its custom TypeScript plugin and type checker.
Simplified Setup: TypeScript is pre-configured in Next.js projects, making it easier to get started.