Node.js is a run-time JavaScript environment built on top of Chrome’s V8 engine. It uses an event-driven, non-blocking I/O model. It is lightweight and so efficient. Node.js has a package ecosystem called npm.
Node.js can be used to build different types of applications such as web application, real-time chat application, REST API server etc. However, it is mainly used to build network programs like web servers, similar to PHP, Java, or ASP.NET. Node.js was developed by Ryan Dahl in 2009.