Node.js is considered non-blocking because it uses an event-driven architecture, allowing it to handle multiple operations at once without waiting for any one task to complete. This leads to improved performance and responsiveness in applications.

In traditional web servers, each request is processed sequentially, blocking the server until the operation completes. This can lead to slow response times, particularly when handling I/O operations such as database queries or file system interactions. Node.js addresses this issue by implementing a non-blocking I/O model, allowing it to initiate operations and continue executing code without waiting for the operation to finish.

The core of this functionality lies in the event loop, which is a single-threaded loop that manages asynchronous calls. When an operation is initiated, Node.js registers a callback function and moves on to the next task. Once the operation completes, the event loop calls the callback, effectively allowing multiple operations to be processed simultaneously. This design is particularly beneficial for applications that require real-time data processing, such as chat applications or online gaming, where fast performance is crucial.

Additionally, the non-blocking nature of Node.js leads to better resource utilization. Developers can create highly scalable applications that serve numerous clients with minimal overhead, making it ideal for microservices architecture and cloud-based services. As a result, Node.js is a strong choice for developers looking to build high-performance, scalable applications that can handle a large number of simultaneous connections efficiently.