When you work with Node.js, you benefit from its ability to handle many tasks at once without waiting for each to finish before starting the next. This is possible because of a library called libuv. Libuv is a core part of Node.js, designed to provide an efficient way to handle asynchronous input and output (I/O) operations. Asynchronous I/O means that Node.js can start a task, such as reading a file or making a network request, and then move on to other work while waiting for the task to complete. Once the task is finished, Node.js is notified and can process the results. This approach helps Node.js handle many connections and requests efficiently, making it ideal for building scalable network applications.

Libuv is written in C and acts as a bridge between the JavaScript code you write and the underlying operating system. It manages low-level operations like file system access, network communication, and timers, all without blocking the main thread. This means your applications remain responsive, even when performing time-consuming operations. By relying on libuv, Node.js can support thousands of concurrent connections, making it a popular choice for web servers, APIs, and real-time applications.