What is a Module ?
                A module in Python is a file that contains Python code - such as variables, functions, classes, or constants - that can be reused in another program.

A module is simply a .py file


Why are modules needed ?

Modules allow us to:

  • split large programs into smaller files
  • reuse code across multiple projects
  • improve maintainability
  • collaborate on team projects

Types of Modules :
              Built in Modules
              External (Third Party) Modules
              User - Defined Modules

Built in Modules :
              These modules come pre-installed with Python.
               Some of them are math, random, datetime etc 

Python 
import math print(math.sqrt(25)) #output 5.0


External Modules :
                Installed using pip. Some of them are numpy, pandas, requests etc. 

Python 
import requests print(requests.__version__)


User Defined Modules :
                A module created by the programmer.
File : mymodule.py

Python 
def greet(name): print("Hello", name)


File: main.py

Python 
import mymodule mymodule.greet("Rahul") #output Hello Rahul