🧺 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
| Rule | Example |
|---|---|
| Must start with a letter or underscore | user, _name |
| Cannot start with a number | ❌ 1name |
| Can contain letters, numbers, underscores | user_1, score2 |
| Cannot be a keyword | ❌ class, def, if |
🔍 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
| Concept | Description |
|---|---|
Declared with = | x = 10, name = "Alice" |
| Type auto-detected | No need to declare type |
| Mutable by default | Can change value/type later |
| Case-sensitive | Name ≠ name |
| Naming follows rules | Only letters, digits, underscores allowed |
❓ 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.
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