Node.js is server side runtime environment that lets us use JavaScript for development of backend applications
- Module is the only way to install any library in Node.js application
 
- Basically module in Node.js is a functionality which is organised in a single or multiple JavaScript file and can be reused throughout the Node.js application
 
- There are 3 categories of modules:
 
- Core modules: They are in-built and you can use them without any installation
 
- User defined modules: They are created by you and you can reuse them in rest of your application
 
- Node Package Manager: These include a group of Modules or packages, developed by other developers, which can be used in your application by installing them
 
- We usually include/install a library(module) using following syntax:
 
-  ES5: var module = require('module_name')
 
-  ES6: import {module} from ‘module_name’
 
- The require() function mentioned here returns an object, function, property or any other JavaScript type, depending on what is mentioned in module
 
I hope this clears your doubt:)
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