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🧠 What is a Variable?

A variable is a named space in memory used to store information. Think of it as a label on a jar — the label (variable name) helps you identify what's inside (the value).

name = "Alice"
age = 25

Here, name and age are variables that store a string ("Alice") and a number (25), respectively.

🔤 Types of Variables

Different programming languages support different data types. Common types include:

• Integer (int): Whole numbers (e.g., 1, 100, -5)
• Float: Decimal numbers (e.g., 3.14, -0.01)
• String (str): Text (e.g., "hello", "123")
• Boolean (bool): True or False values

is_student = True       # Boolean
height = 5.9            # Float

🧾 Rules for Naming Variables

Good variable names make your code easier to read and understand. Here are some basic rules:

• ✅ Start with a letter or underscore (_)
• ✅ Use only letters, numbers, and underscores
• ❌ Don’t start with a number
• ❌ Avoid using reserved keywords (like if, while, class)

# Valid names
user_name = "john"
score = 98

# Invalid names
# 1name = "wrong"  ❌
# if = 5           ❌

🔄 Variables are Changeable

You can change the value of a variable at any time in your code:

score = 50
score = 75  # Now the value of score is 75

🧪 Why Variables Matter

Variables let your programs be dynamic and flexible. Instead of hardcoding values, you can use variables to:

• Accept input from users
• Store results from calculations
• Control program flow

name = input("Enter your name: ")
print("Hello, " + name + "!")

🌐 Final Thoughts

Variables are the foundation of any programming language. Mastering how they work is the first step to becoming a skilled coder. Start experimenting with them in small programs — you'll be surprised at how powerful they can be!