Node.js is a powerful JavaScript runtime that allows developers to run JavaScript code on the server side. Traditionally, JavaScript was used only in web browsers, but with Node.js, it can be used to build scalable network applications. This makes it easier to create fast and efficient web servers, as it can handle many connections simultaneously without slowing down. One of the key features of Node.js is its non-blocking, event-driven architecture. This means that it can process multiple requests at the same time, making it ideal for applications that require real-time data, like chat apps or online gaming. With a vast ecosystem of libraries and frameworks, Node.js has become a popular choice for developers worldwide.