Variables are fundamental building blocks in programming that allow us to store and manipulate data. Think of them as labeled containers where you can put different types of information and retrieve them whenever needed. This lesson will teach you how to create variables, follow naming conventions, and work with different data types in Python.

Variables are like labeled boxes in a warehouse. Each box (variable) has a name written on it, and you can put different items (data) inside. When you need something specific, you just look for the box with the right label. In programming, variables let you store numbers, text, lists, and other types of data.

Creating variables in Python is straightforward - you simply choose a name and assign a value using the equals sign (=). Python will automatically determine the data type based on the value you provide.

# Creating different types of variables
name = "Alice"
age = 25
height = 5.6
is_student = True
favorite_colors = ["blue", "green", "purple"]

# Using variables in output
print("Name:", name)
print("Age:", age)
print("Height:", height, "feet")
print("Is student:", is_student)
print("Favorite colors:", favorite_colors)

# Variables can be updated
age = 26
print("Updated age:", age)

Notice how we can store different types of data in variables - text (strings), whole numbers (integers), decimal numbers (floats), true/false values (booleans), and even collections of items (lists). Python handles all the complexity behind the scenes.

Python has specific rules for naming variables that you must follow, plus some best practices that will make your code more readable and maintainable.

Required Rules (Your code will not work if you break these):

Best Practices (Follow these for clean, readable code):

# Good variable names
first_name = "John"
student_age = 20
total_score = 95.5
is_homework_complete = True

# Poor variable names (avoid these)
n = "John"           # Too short, unclear
studentAge = 20      # camelCase (not Python style)
ts = 95.5           # Abbreviation, unclear
x = True            # Meaningless name

Python supports several built-in data types that cover most programming needs. Understanding these types will help you choose the right tool for storing different kinds of information.

Strings (Text Data):

Strings represent text and are enclosed in either single or double quotes. You can perform various operations on strings like combining them, finding their length, or formatting them with variables.

# Different ways to create strings
message = "Hello, World!"
name = 'Alice'
quote = "She said, 'Python is awesome!'"

# String operations
full_name = "John" + " " + "Doe"        # Concatenation
greeting = f"Hello, {name}!"            # f-string formatting
length = len(message)                   # Get string length
uppercase = message.upper()             # Convert to uppercase

print(full_name)    # Output: John Doe
print(greeting)     # Output: Hello, Alice!
print(length)       # Output: 13
print(uppercase)    # Output: HELLO, WORLD!

Numbers (Integers and Floats):

Python distinguishes between integers (whole numbers) and floats (decimal numbers). You can perform mathematical operations on both types, and Python will handle the calculations automatically.

# Integers (whole numbers)
age = 25
year = 2024
score = 100

# Floats (decimal numbers)
height = 5.9
price = 19.99
temperature = -2.5

# Mathematical operations
addition = 10 + 5           # Result: 15
subtraction = 10 - 3        # Result: 7
multiplication = 4 * 6      # Result: 24
division = 15 / 3           # Result: 5.0 (always returns float)
floor_division = 17 // 5    # Result: 3 (integer division)
exponentiation = 2 ** 3     # Result: 8
modulo = 17 % 5            # Result: 2 (remainder)

print(f"Addition: {addition}")
print(f"Division: {division}")
print(f"Floor division: {floor_division}")
print(f"Modulo: {modulo}")

Booleans (True/False Values):

Booleans represent truth values and are essential for making decisions in your programs. They can only be True or False (note the capitalization).

# Boolean variables
is_sunny = True
is_raining = False
has_homework = True

# Booleans from comparisons
is_adult = age >= 18
is_passing_grade = score >= 70
is_weekend = day == "Saturday" or day == "Sunday"

print(f"Is adult: {is_adult}")
print(f"Is passing: {is_passing_grade}")

# Using booleans in conditions
if is_sunny:
    print("Great day for a walk!")
if not is_raining:
    print("No need for an umbrella!")

Understanding variables and data types is crucial for all future Python programming. These concepts form the foundation upon which you will build more complex programs. Practice creating variables with different data types and experimenting with operations to solidify your understanding.