The main difference between local and global packages is this:

• local packages are installed in the directory where you run npm install <package-name>, and they are put in the node_modules folder under this directory
• global packages are all put in a single place in your system (exactly where depends on your setup), regardless of where you run npm install -g <package-name>

In your code, they are both required in the same way:

require('package-name')

so when should you install in one way or another?

In general, all packages should be installed locally.

This makes sure you can have dozens of applications in your computer, all running a different version of each package if needed.

Updating a global package would make all your projects use the new release, and as you can imagine this might cause nightmares in terms of maintenance, as some packages might break compatibility with further dependencies, and so on.

All projects have their own local version of a package, even if this might appear like a waste of resources, it’s minimal compared to the possible negative consequences.

A package should be installed globally when it provides an executable command that you run from the shell (CLI), and it’s reused across projects.

You can also install executable commands locally and run them using npx, but some packages are just better installed globally.

Great examples of popular global packages which you might know are

• npm
• create-react-app
• vue-cli
• grunt-cli
• mocha
• react-native-cli
• gatsby-cli
• forever
• nodemon

You probably have some packages installed globally already on your system. You can see them by running

npm list -g --depth 0

on your command line.

Lessons in this unit:

0:	Introduction
1:	How to use or execute a package installed using npm
2:	npm dependencies and devDependencies
3:	How to fix the "Missing write access" error when using npm
4:	npm can install packages in the parent folder
5:	Install an older version of an npm package
6:	Find the installed version of an npm package
7:	How to test an npm package locally
8:	▶︎ npm global or local packages
9:	What are peer dependencies in a Node module?
10:	`npm run dev` is a long-running program
11:	Semantic Versioning using npm
12:	Uninstalling npm packages with `npm uninstall`
13:	An introduction to the npm package manager
14:	The npx Node Package Runner
15:	The package.json guide
16:	The package-lock.json file
17:	What is pnpm?
18:	Should you commit the node_modules folder to Git?
19:	Update all the Node dependencies to their latest version
20:	Where does npm install the packages?
21:	Bumping Node.js dependencies
22:	Run package.json scripts upon any file changes in a folder