What is Python?

Python is a high-level, interpreted programming language known for its simplicity and readability. Created by Guido van Rossum and first released in 1991, Python has become one of the most popular programming languages worldwide.

Why Python?

  • Easy to Learn: Python's syntax is designed to be readable and straightforward
  • Versatile: Used in web development, data science, artificial intelligence, automation, and more
  • Large Community: Extensive libraries and active community support
  • Cross-Platform: Runs on Windows, macOS, Linux, and other operating systems

Installation & Setup

Installing Python

  1. Visit the official Python website: https://www.python.org/downloads/
  2. Download the latest version (Python 3.11 or newer recommended)
  3. Run the installer and make sure to check "Add Python to PATH"

Verification

After installation, verify Python is working:

python --version
# or
python3 --version

Integrated Development Environments (IDEs)

1. IDLE (Python's Built-in IDE)

  • Comes with Python installation
  • Simple and lightweight
  • Good for beginners

2. VS Code (Visual Studio Code)

  • Free, powerful, and widely used
  • Excellent Python extension
  • Great for learning and professional development

3. PyCharm

  • Full-featured IDE by JetBrains
  • Professional version available
  • Excellent debugging tools

4. Jupyter Notebook

  • Interactive coding environment
  • Great for data science and learning
  • Web-based interface

Writing Your First Python Script

Hello World Program

# hello_world.py
print("Hello, World!")
print("Welcome to Python programming!")

Running Python Scripts

Method 1: Command Line

python hello_world.py
# or
python3 hello_world.py

Method 2: Interactive Mode

python
# Then type:
print("Hello, World!")

Comments & Code Style

Comments in Python

# This is a single-line comment

"""
This is a multi-line comment
It can span multiple lines
"""

def greet(name):
    """
    This is a docstring - used to document functions
    """
    return f"Hello, {name}!"

PEP 8 Style Guidelines

PEP 8 is Python's official style guide. Key rules:

# Good style examples:

# Use meaningful variable names
student_name = "Alice"
student_age = 20

# Use snake_case for variables and functions
def calculate_average(numbers):
    return sum(numbers) / len(numbers)

# Use PascalCase for classes
class Student:
    def __init__(self, name, age):
        self.name = name
        self.age = age

# Indentation: 4 spaces (never tabs)
if student_age >= 18:
    print("Adult student")
else:
    print("Minor student")

# Line length: maximum 79 characters
# If line is too long, break it:
total_score = math_score + english_score + science_score + \
              history_score + art_score

Exercise: First Python Program

Create a program that: 1. Asks for the user's name 2. Asks for their age 3. Greets them and tells them their age in days

# first_program.py

# Get user input
name = input("What is your name? ")
age = input("What is your age? ")

# Convert age to integer and calculate days
age_in_days = int(age) * 365

# Display results
print(f"Hello, {name}!")
print(f"You are {age} years old.")
print(f"That's approximately {age_in_days} days!")

# Add some personality
if int(age) >= 18:
    print("You are an adult!")
else:
    print("You are still growing up!")

Key Takeaways

  1. Python is beginner-friendly with readable syntax
  2. Multiple IDEs available - choose one that feels comfortable
  3. Comments help document your code and make it readable
  4. Follow PEP 8 for consistent, professional code style
  5. Start simple with basic programs and gradually add complexity

Next Steps

In the next lesson, we'll explore Python's core syntax including variables, data types, and operators.