Installing bower, grunt, etc... what's the difference between a global (-g) and a local install?

Question

Node.js

Please explain on your fingers ...
What is the difference in terms of the project that I am writing?
It means that, apart from the placement of files during installation, I don’t see (don’t understand) the difference.
Or is it all important if there are a lot of projects? Or it is necessary to put for each project (not globally)?
As for questions, you have already understood that when there is no clarity, then asking is not very successful.

Answer 1

The global setting is usually used for tools. So, after npm i grunt-cli -g, the grunt command will appear in the system.
If this is some kind of library, then it must be installed locally. Among the reasons is that the project can rely on a particular version of the library than interfere with others.