Python installation directory Lib/site-packages

Lib/site-packages, located under the Python root installation directory, contains third party library modules.

Apparently, installing a module with pip, causes the package to be installed under <PY-INSTALL-DIR>/Lib/site-packages.

The paths of these modules is added to the module search path by the script (module?) Lib/site.py.

A wheel file is a zip file that can be extracted into Lib/site-packages.