Express.js is a popular web application framework for Node.js, which is a JavaScript runtime used for building server-side applications. Express.js makes it easier to build web applications by providing a set of tools and functionalities that help in routing requests, handling HTTP requests and responses, and managing middleware.

For beginners, Express.js provides a simple and flexible way to build web applications using Node.js. It is easy to learn and has a wide range of community support, making it an excellent choice for building web applications quickly.

Some of the key features of Express.js that make it popular among developers include:

• Routing: Express.js provides a simple way to define routes for handling incoming HTTP requests.

• Middleware: Express.js allows you to use middleware functions to perform operations on HTTP requests and responses, such as logging, parsing data, and handling errors.

• Template engines: Express.js supports various template engines like EJS, Pug, and Handlebars, which make it easy to generate dynamic HTML content.

• Error handling: Express.js provides built-in error handling to handle runtime errors and exceptions.

Overall, Express.js is a great choice for beginners looking to learn web application development with Node.js, and it provides a solid foundation for building robust and scalable applications