🧺 Python Variables: Syntax, Rules, and Best Practices (2025)

🔍 What Are Variables in Python?

Variables in Python are named containers that store data values. You can use them to store anything—numbers, text, lists, and more.

✅ Key Features of Python Variables

• No need to declare the type – Python detects it automatically.
• Created when first assigned a value
• Variables can change type during runtime.

📝 Syntax to Create a Variable

x = 10          # integer
name = "Alice"  # string
pi = 3.14       # float

Python uses the = operator to assign values to variables.

🔁 Variables Are Mutable (Except Immutable Types)

x = 5
x = "Hello"   # valid — x now refers to a string

Python variables are dynamic, meaning they can hold any type of data.

📛 Variable Naming Rules

🔍 Valid vs Invalid Examples

# ✅ Valid
user_name = "Bob"
_total = 100
age2 = 30

# ❌ Invalid
2score = 95         # starts with number
my-name = "Jane"    # uses dash
def = "keyword"     # reserved word

🧠 Best Practices for Variable Naming

• Use descriptive names: user_age, total_price
• Use lowercase with underscores (snake_case)
• Avoid single-letter names (except for loops like i, j)

📌 Summary – Python Variables

❓ FAQs – Python Variables

❓ What is a variable in Python?

A variable in Python is a named memory location used to store data such as numbers, text, lists, or other types.

❓ Do I need to declare the type of a variable in Python?

No. Python uses dynamic typing, so the type is automatically assigned based on the value you assign.

❓ How do I assign a value to a variable in Python?

Use the assignment operator =:

x = 10
name = "Alice"

❓ Can I change the value of a variable after assigning it?

Yes. Variables in Python are mutable and you can reassign them with new values—even of different types.

❓ What are the rules for naming variables in Python?

• Must start with a letter or underscore
• Cannot start with a number
• Only letters, numbers, and underscores are allowed
• Cannot use Python reserved keywords (like class, def)

❓ Is Python case-sensitive with variables?

Yes. Name, name, and NAME are three different variables.