Learn Python 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

Code Example 2: Invalid Variable Names

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:

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

Code Example 1: Camel Case

Code Example 2: Camel Case with Numbers

Code Example 3: Camel Case Usage

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

Code Example 1: Pascal Case

Code Example 2: Pascal Case Usage

Code Example 3: Pascal Case in Classes

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

Code Example 1: Snake Case

Code Example 2: Snake Case with Numbers

Code Example 3: Recommended Style

Python Standard

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

Which Naming Style Should You Use in Python?

Style	Usage 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.

Exercise

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