How a project is installed with npm install command

Question

$ sudo npm install -g phonegap

How phonegap is installed when I run this command.Reason for my doubt is that, we are not mentioning any ip here, then how and from where it grabs the content? consider phone gap is just an example.

I read this but not describes the details.

Answer 1

NPM grabs and installs its packages from www.npmjs.org.