Node.js® is a JavaScript runtime built on Chrome’s V8 JavaScript engine.
The V8 engine is the open-source JavaScript engine that runs in Google Chrome and other Chromium-based web browsers, including Brave, Opera, and Vivaldi. It was designed with performance in mind and is responsible for compiling JavaScript directly to native machine code that your computer can execute.
designed to automate the process of developing a modern JavaScript application.
Node is particularly suited to building applications that require some form of real-time interaction or collaboration — for example, chat sites, or apps such as CodeShare, where you can watch a document being edited live by someone else.
Aside from speed and scalability, an often-touted advantage of using JavaScript on a web server — as well as in the browser — is that your brain no longer needs to switch modes. You can do everything in the same language, which, as a developer, makes you more productive (and hopefully, happier). For example, you can easily share code between the server and the client.