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.
MongoDB is a NoSQL document-oriented database that is widely used for building scalable and flexible web applications. It integrates well with Node.js and allows developers to work with data using JavaScript objects.
NPM is the package manager for Node.js, which allows developers to easily install, update, and manage the dependencies for their Node.js applications.