Python Introduction Notes — Complete Study Guide

• Creator: Guido van Rossum
• Year: First released in 1991
• Named after: Monty Python's Flying Circus (comedy show, NOT the snake)
• Python 2: Released 2000, discontinued 2020
• Python 3: Released 2008, current version (3.12+ in 2026)
• Organization: Maintained by Python Software Foundation (PSF)
• License: Open source (free to use, modify, distribute)

1. Easy to Learn — reads like English, minimal syntax
2. Interpreted — no compilation step, runs line by line
3. Dynamically Typed — no need to declare variable types
4. Object-Oriented — supports classes, inheritance, polymorphism
5. Open Source — free to download, use, and distribute
6. Cross-Platform — runs on Windows, Mac, Linux without changes
7. Extensive Libraries — 400,000+ packages on PyPI
8. Large Community — millions of developers, easy to find help
9. High-Level Language — no memory management needed
10. Garbage Collection — automatic memory cleanup
11. Supports Multiple Paradigms — OOP, functional, procedural
12. Embeddable — can be embedded in C/C++ programs
13. Extensible — can call C/C++ code for performance
14. GUI Support — Tkinter, PyQt, Kivy for desktop apps
15. Database Support — MySQL, PostgreSQL, MongoDB, SQLite
16. Web Development — Django, Flask, FastAPI frameworks
17. AI/ML Support — TensorFlow, PyTorch, Scikit-learn
18. Data Science — Pandas, NumPy, Matplotlib
19. Automation — Selenium, scripting, task automation
20. Rapid Prototyping — build MVPs faster than any other language

Windows Installation:

1. Go to python.org/downloads
2. Click "Download Python 3.12.x" (latest version)
3. IMPORTANT: Check ✅ "Add Python to PATH" during installation
4. Click "Install Now"
5. Open Command Prompt → type python --version → should show version
6. Type python → you're in the Python shell! Type print("Hello")

Online (No Installation):

• replit.com — best for beginners (free, instant)
• Google Colab — best for data science (free GPU)
• Programiz Online — simple editor + output

Variables & Data Types:

# Variables (no type declaration needed)
name = "Rahul"        # str (string)
age = 20              # int (integer)
height = 5.8          # float (decimal)
is_student = True     # bool (boolean)
marks = [85, 92, 78]  # list
info = {"name": "Rahul", "age": 20}  # dict

# Print
print(f"Name: {name}, Age: {age}")

# Input
user_name = input("Enter your name: ")

# Type conversion
num = int("42")       # string to int
text = str(100)       # int to string

Operators:

# Arithmetic: +  -  *  /  //  %  **
print(10 / 3)    # 3.333 (float division)
print(10 // 3)   # 3 (integer division)
print(10 % 3)    # 1 (remainder)
print(2 ** 10)   # 1024 (power)

# Comparison: ==  !=  >  <  >=  <=
# Logical: and  or  not
# Assignment: =  +=  -=  *=  /=

# Method 1: For loop with range
for i in range(1, 11):
    print(i)

# Method 2: While loop
i = 1
while i <= 10:
    print(i)
    i += 1

# Method 3: One-liner
print(*range(1, 11))

# Method 4: Join as string
print(", ".join(str(i) for i in range(1, 11)))
# Output: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10