required packages for GUI in Python

[Skaperen]

while looking through google for tutorials to learn GUI for Python, i saw mentioned some packages the need to be installed. my question is this: are any packages needed when the end user runs a GUI app developed in Python? for command line, the basic need (Python itself) is required unless the app has further needs. do GUI apps in Python have this further need? how much of GUI needs are included with typical major OSes and distributions (most already include Python and some even depend on it).