Node.js is an open-source, cross-platform runtime environment that allows developers to execute JavaScript code outside of a web browser. Developed by Ryan Dahl in 2009, Node.js is built on the V8 JavaScript engine used in Google Chrome. It is designed for building fast, scalable, and efficient server-side applications. One of the key features of Node.js is its non-blocking, event-driven architecture, which makes it ideal for handling multiple simultaneous connections with high performance. This makes it particularly suitable for real-time applications such as chat apps, APIs, streaming services, and web servers. Node.js uses a single-threaded event loop model, enabling lightweight and efficient execution without the overhead of traditional multi-threaded servers. With a vast ecosystem of open-source packages available via npm (Node Package Manager), developers can easily add functionality to their applications. Overall, Node.js empowers developers to use JavaScript for full-stack development, unifying backend and frontend code in a seamless workflow.