What does module in python do? how to install it? !

A Python module is an extension file which contains programmable resources for a given translation unit. This is very much like a header file in C and C++, it's modularized data. For example, say I wanted to write a server/client script. I can't easily do so with Python out of the box. I would require the "socket" module which contains all of the functions, variables and data structures which allow for network programming.

network.py

from socket import *

s = socket(AF_INET, SOCK_STREAM)
(...)

It can sometimes be called a process chart.