snake_case Guide

What is snake_case?

snake_case is a naming convention where words are separated by underscores (_) and all letters are lowercase. It gets its name from the visual appearance of the underscores connecting words like a snake on the ground.

Examples:

first_name
get_user_data
total_price_with_tax
is_valid_email

When to Use snake_case

Python: The standard for variables, functions, and file names
Ruby: Variables and method names
Rust: Variables and function names
Database: Table names and column names (SQL)
File names: Especially on Unix/Linux systems
Environment variables: Configuration settings

Examples in Code

Python Variables:

user_name = "John Doe"
total_items = 42
is_logged_in = True

Function Names:

def calculate_total_price():
    pass

def get_user_by_id(user_id):
    pass

def validate_email_address(email):
    pass

Database Schema:

CREATE TABLE user_accounts (
    user_id INT PRIMARY KEY,
    first_name VARCHAR(50),
    last_name VARCHAR(50),
    email_address VARCHAR(100)
);

Comparison with Other Conventions

Convention

snake_case

camelCase

PascalCase

kebab-case

CONSTANT_CASE

Example

user_nameuserNameUserNameuser-nameUSER_NAME

Best Practices

✓ Use descriptive names: user_account_balance instead of uab
✓ Keep consistent with language conventions
✓ Perfect for database column names
✓ Excellent for file names (cross-platform compatible)
✓ Use UPPER_SNAKE_CASE for constants
✗ Don't mix with camelCase in the same context
✗ Avoid starting or ending with underscores (unless specific convention)
✗ Don't use double underscores (__ reserved in Python)

Language-Specific Guidelines

Python (PEP 8)

snake_case is the standard for function names, variable names, and module names. Use UPPER_SNAKE_CASE for constants.

def my_function():
    MAX_CONNECTIONS = 100

Ruby

Ruby uses snake_case for methods, variables, and file names. Class names use PascalCase.

def calculate_total
  # method body
end

SQL Databases

snake_case is widely adopted for table names and column names across most SQL databases.

SELECT first_name, last_name FROM user_accounts;

Why Use snake_case?

• Readability: Underscores clearly separate words
• Convention: Standard in Python, Ruby, and databases
• Accessibility: Easier to read for some people than camelCase
• Case-insensitive: Works in case-insensitive systems
• File names: Safe for all operating systems
• No ambiguity: Clear word boundaries unlike camelCase

Examples in Code

Python Variables:

user_name = "John Doe"
total_items = 42
is_logged_in = True

Function Names:

def calculate_total_price():
    pass

def get_user_by_id(user_id):
    pass

def validate_email_address(email):
    pass

Database Schema:

CREATE TABLE user_accounts (
    user_id INT PRIMARY KEY,
    first_name VARCHAR(50),
    last_name VARCHAR(50),
    email_address VARCHAR(100)
);

Best Practices

✓ Use descriptive names: user_account_balance instead of uab

✓ Keep consistent with language conventions

✓ Perfect for database column names

✓ Excellent for file names (cross-platform compatible)

✓ Use UPPER_SNAKE_CASE for constants

✗ Don't mix with camelCase in the same context

✗ Avoid starting or ending with underscores (unless specific convention)

✗ Don't use double underscores (__ reserved in Python)

Language-Specific Guidelines

Python (PEP 8)

snake_case is the standard for function names, variable names, and module names. Use UPPER_SNAKE_CASE for constants.

def my_function():
    MAX_CONNECTIONS = 100

Ruby

Ruby uses snake_case for methods, variables, and file names. Class names use PascalCase.

def calculate_total
  # method body
end

SQL Databases

snake_case is widely adopted for table names and column names across most SQL databases.

SELECT first_name, last_name FROM user_accounts;

Why Use snake_case?

• Readability: Underscores clearly separate words

• Convention: Standard in Python, Ruby, and databases

• Accessibility: Easier to read for some people than camelCase

• Case-insensitive: Works in case-insensitive systems

• File names: Safe for all operating systems

• No ambiguity: Clear word boundaries unlike camelCase

What is snake_case?

When to Use snake_case

Examples in Code

Comparison with Other Conventions

Best Practices

Language-Specific Guidelines

Python (PEP 8)

Ruby

SQL Databases

Why Use snake_case?

Related Guides

camelCase Guide

kebab-case Guide

CONSTANT_CASE Guide

dot.case Guide

snake_case Guide

What is snake_case?

When to Use snake_case

Examples in Code

Comparison with Other Conventions

Best Practices

Language-Specific Guidelines

Python (PEP 8)

Ruby

SQL Databases

Why Use snake_case?

Related Guides

camelCase Guide

kebab-case Guide

CONSTANT_CASE Guide

dot.case Guide