If Activities takes a long time such as a file access, database operation or network communication then they put aside until the results are ready and available to the callback function, instead of waiting for the completion of these tasks. It provides better throughput and scalability to the applications.
Node.js has an open source community which produces excellent applications to add more capabilities at the Node.js. One of the most famous application Socket.io which manages the connection between the server and client is developed by the Node.js community.
The event-driven architecture of Node.js makes it appropriate for the real-time applications such as games and chat applications. The synchronization of frontend and backend process is improved after the use of Node.js.
Currently Node.js web application are fasted application at the world in comprasion of other popular backend programming languages like PHP, Java or .Net. It responds to the request in the minimum time in comprasion of PHP.
Node.js is widely adopted by the startups which need to handle millions of queries at a time. Many of the established companies such as Paypal, LinkedIn, Yahoo, eBay, and Netflix are using Node.js.