Express.js is a popular web framework for Node.js that provides a set of tools and libraries for building web applications. It simplifies the development process and provides a flexible architecture for building scalable and maintainable web applications.
Socket.io is a library that allows developers to build real-time applications using Node.js. It provides a set of tools for building real-time communication channels between the server and client.
NPM is the package manager for Node.js, which allows developers to easily install, update, and manage the dependencies for their Node.js applications.