Node.js tutorial
Node.js is JavaScript runtime environment built on Chrome's V8 JavaScript engine. It is an open-source and cross-platform and allows to execute JavaScript code outside a web browser.
JavaScript is the only language that Node.js supports natively, but many compile-to-JS languages are available. As a result, Node.js applications can be written in CoffeeScript, Dart, TypeScript, ClojureScript and others.
Node.js is primarily used to build network programs such as Web servers. The most significant difference between Node.js and PHP is that most functions in PHP block until completion, while Node.js functions are non-blocking, i.e. commands execute concurrently or even in parallel and use callbacks to signal completion or failure.
You can download and install Node.js from official site for all popular OS: MacOs, Linux, Microsoft Windows.