Node.js is a JavaScript runtime built on Chrome's V8 JavaScript engine. Key points: Server-side JavaScript execution Asynchronous, event-driven architecture Non-blocking I/O model Large ecosystem (npm package manager) Cross-platform compatibility Ideal for real-time applications Used for web servers, APIs, microservices Supports full-stack JavaScript development Popular for scalable network applications Extensible through modules Node.js enables developers to use JavaScript for both client-side and server-side programming, facilitating efficient and fast application development.