What is Snake Case? Definition, Examples & Where It's Used

What is Snake Case?

snake_case is a naming convention where words are written in all lowercase and separated by underscores (_). It gets its name from the flat, ground-level appearance of the underscores — like a snake lying on the ground.

Examples: first_name, get_user_by_id, background_color, max_retry_count

Origin of snake_case

Snake case has been used in Unix-based systems and scripting languages for decades. Python's PEP 8 style guide, published in 2001, formalized its use for Python code, which significantly boosted its popularity.

Where snake_case is Used

Programming Languages

• Python — PEP 8 mandates snake_case for variables, functions, module names, and method names
• Ruby — community standard for methods, variables, and file names
• PHP — commonly used for function names (though not strictly enforced)
• Rust — convention for variable and function names

Databases

• SQL — column names, table names, and stored procedure names (e.g., user_id, created_at)
• PostgreSQL — strongly prefers snake_case for identifiers

File Systems

• Linux/macOS file names — underscores over spaces for shell compatibility
• Python module files — e.g., my_module.py, data_processor.py

Variations of snake_case

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snake_case vs Other Conventions

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Best Practices

• Use lowercase only — my_variable, not My_Variable
• Keep names descriptive — get_user_by_id is better than g_u_b_i
• Avoid excessive underscores — get__user___name is hard to read
• Use SCREAMING_SNAKE_CASE for constants and environment variables