Standard Library Modules

Python comes with many useful modules already installed.

You do not need to download them.

This collection is called the standard library.

What Is the Standard Library?

The standard library is a set of built-in modules that come with Python.

They help with:

• math
• dates
• random values
• files
• operating system tasks
• JSON
• CSV
• and much more

Why It Matters

Instead of writing everything yourself, you can use ready-made tools.

This saves time and effort.

Common Standard Library Modules

1. math

Used for math operations.

import math

print(math.sqrt(16))
print(math.pi)

Output

4.0
3.141592653589793

2. random

Used for random choices.

import random

print(random.randint(1, 10))

Example Output

7

(Output may be different.)

3. datetime

Used for dates and time.

from datetime import date

today = date.today()
print(today)

Example Output

2026-04-30

4. os

Used for folders and file paths.

import os

print(os.getcwd())

Example Output

/Users/student/project

5. json

Used for JSON files.

import json

data = {"name": "Tom"}

print(json.dumps(data))

Output

{"name": "Tom"}

6. csv

Used for CSV files.

import csv

How to Explore Modules

Use:

dir(math)

This shows items inside the module.

Common Beginner Tip

You do not need to memorize every module.

Learn how to search documentation and use what you need.

Code Along

Import random.

Print a random number from 1 to 5.

Mini Challenge

Use:

• math
• random

Tasks:

• Print square root of 81
• Print random number from 1 to 3

Expected output example:

9.0
2

Real World Use Case

Developers use the standard library daily for automation, dates, math, files, reports, and data processing.

Quiz

1. What is the standard library?
2. Which module helps with dates?
3. Which module helps with random values?
4. Which module helps with JSON?

Assignment

Use three different standard library modules in one small program.

Summary

You learned that Python includes many built-in modules that save time and solve common tasks.