Node.js is a free, open-source, cross-platform JavaScript runtime environment that allows developers to execute JavaScript code outside of a web browser. Historically, JavaScript was confined to running inside web browsers (like Chrome or Safari) to make web pages interactive. Node.js takes Google Chrome’s fast V8 JavaScript engine and wraps it in an environment that runs directly on a computer or server. This means you can use JavaScript to write command-line tools, manage files, and interact with databases.