Where do Python Modules come from? Where are they stored in the file system?

I’m learning about Python Modules and I understand that they must be imported rather than installed to avoid clogging up the works, but I’m not sure where they come from, how to verify their safety, or where to store them in the file system should I decide to make one myself or install one from another source.

If I save a Python document in one part of the file system, will I be able to import objects from that first file into another file saved elsewhere in the file system? Is this somehow remotely related to scope - can I import an object as long as the files share some level of parent?