This document provides an introduction to Node.js, including what it is, its advantages, and how its process model works. Node.js is an open-source JavaScript runtime environment that uses asynchronous programming and non-blocking I/O. It allows building highly scalable server-side applications using JavaScript. Unlike traditional web servers which use threads, Node.js runs in a single process with a single thread and handles I/O asynchronously so it can handle multiple requests concurrently without blocking. This increases performance and scalability compared to traditional threaded servers.