An open-source, cross-platform, back-end JavaScript runtime environment that executes JavaScript code outside a web browser.

"Node.js allows developers to use JavaScript to write command-line tools and for server-side scripting—running scripts server-side to produce dynamic web page content before the page is sent to the user's web browser."

An open-source, cross-platform JavaScript run-time environment that executes JavaScript code outside of a browser.

"Node.js is used to build scalable network applications, particularly web servers."