Common NodeJS modules

Built-in modules:

ls -la /usr/lib/node_modules/npm/node_modules

Example of built-in modules:
fs - to handle filesystem
http - To host an HTTP server
os - To work with the Operating System
events - To handle events
tls - To implement TLS and SSL
url - To parse URL strings

External modules:

ls -la /usr/lib/node_modules

Example of external modules:
express - Fast, unnopinionated, minimalist web framework
react - To create user interfaces
debug - To debug applications
async - To work with asyncronous Javascript
lodash - To work with arrays, objects, strings etc.