The Node.js core literally has hundreds of modules available for you to use while writing your applications. These modules are already compiled into binary and are defined within Node.js source code. These include the following:

• Events
• Filesystems

Just like other languages, the Node.js core also provides an ability to interact with filesystem using the fs module. This module is equipped with different methods for performing different operations on file synchronously as well as asynchronously. Refer chapter 1. Welcome to JavaScript in The Full Stack to learn more about the difference of sync and async. The synchronous methods of fs are suffixed by the keyword Sync for instance readFileSync. For all reviewing the module in depth refer the following link : https://nodejs.org/api/fs.html.