Node.js is an open-source, server-side JavaScript runtime environment built on Chrome’s V8 JavaScript engine. It enables developers to execute JavaScript code on the server, allowing for non-blocking, event-driven, and highly scalable applications. Node.js provides a rich set of built-in libraries and modules, making it ideal for developing server-side applications, APIs, real-time applications, and microservices. Its single-threaded, event-driven architecture allows for efficient handling of concurrent connections, making it well-suited for applications with high levels of I/O operations. Node.js has gained significant popularity in recent years due to its performance, flexibility, and vibrant community support.