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Python Variable Names

Variable names in Python are used to identify data stored in memory. Choosing correct and meaningful variable names makes code readable, clean, and professional.
Python follows specific naming rules and conventions that every developer should follow.

Rules for Python Variable Names

Before learning naming styles, understand these basic rules:
  • A variable name must start with a letter (a–z, A–Z) or underscore (_)
  • It cannot start with a number
  • It can contain letters, numbers, and underscores
  • Variable names are case-sensitive
  • Python keywords cannot be used as variable names

Code Example 1: Valid Variable Names

python
name = "Python"
_version = 3
user1 = "Admin"

Code Example 2: Invalid Variable Names

python
# 1name = "Error"
# user-name = "Error"
# class = "Error"

Multi Words Variable Names

When a variable name contains more than one word, it must be written in a readable format. Python does not allow spaces in variable names.
Instead of:
text
user name
We use naming conventions.
Key Idea

Multi-word variable names improve clarity and understanding.

Camel Case

In Camel Case, the first word starts with a lowercase letter, and each new word starts with a capital letter.

Format

text
myVariableName

Code Example 1: Camel Case

python
userName = "Jayesh"
accountBalance = 5000

Code Example 2: Camel Case with Numbers

python
userAge1 = 25

Code Example 3: Camel Case Usage

python
totalMarksObtained = 450
Usage

Camel Case is commonly used in Java and JavaScript, not preferred in Python.

Pascal Case

In Pascal Case, every word starts with a capital letter, including the first one.

Format

text
MyVariableName

Code Example 1: Pascal Case

python
StudentName = "Amit"
TotalScore = 95

Code Example 2: Pascal Case Usage

python
EmployeeSalary = 60000

Code Example 3: Pascal Case in Classes

python
class StudentDetails:
    pass
Best Practice

Pascal Case is mainly used for class names in Python.

Snake Case

In Snake Case, words are separated using underscores (_), and all letters are usually lowercase.

Format

text
my_variable_name

Code Example 1: Snake Case

python
user_name = "Python"
account_balance = 10000

Code Example 2: Snake Case with Numbers

python
student_mark_1 = 85

Code Example 3: Recommended Style

python
total_order_count = 120
Python Standard

Snake Case is the recommended naming convention in Python (PEP 8).

Which Naming Style Should You Use in Python?

StyleUsage in Python
Camel Case❌ Not recommended
Pascal Case✅ Class names
Snake Case✅ Variables and functions
Learning Insight

Following naming conventions makes your code Pythonic and professional.

Summary

  • Variable names identify stored data
  • Multi-word names need proper formatting
  • Camel Case uses capital letters inside words
  • Pascal Case capitalizes every word
  • Snake Case uses underscores and lowercase
  • Snake Case is best for Python variables

Exercise

  • Create three variables using Snake Case
  • Create a class using Pascal Case
  • Identify incorrect variable names and fix them