1. Reserved Keywords

These are special words Python uses for its syntax and cannot be redefined as variable names. Examples include:

To see the full list, you can use:

2. Names Starting with Numbers

Variable names cannot begin with a number. For example:

3. Special Characters

Variable names cannot include special characters like @, #, !, %, etc. Examples:

4. Spaces

Variable names cannot include spaces. Use underscores (_) instead:

5. Names Already in Use by Built-in Functions

Using the names of Python’s built-in functions (e.g., print, len, type, list) is not technically illegal but is strongly discouraged because it can cause bugs and confusion:

To avoid issues, stick to descriptive, lowercase, and snake_case variable names that don't conflict with these rules!

Python Variables Lesson