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non-public name

In Python, a non-public name refers to the name of a variable, function, method, or attribute that is intended for internal use within a module or a class. These names are prefixed with an underscore (_) to signal that you shouldn’t access or modify them directly from outside the module or class.

Python doesn’t enforce strict access restrictions. Using a leading underscore is a naming convention that communicates the intended use of certain elements.

By marking a name as non-public, you indicate that that name is an implementation detail and can change in the future and isn’t intended to be used as part of the code’s public interface.

Example

Here’s an example of non-public names in a Python class:

Python 
class DemoClass:
    def __init__(self, value):
        self._hidden_value = value  # Non-public attribute

    def get_value(self):
        return self._hidden_value

# Usage
demo = DemoClass(42)
demo.get_value()  # Output: 42
# Don't do this
print(demo._hidden_value)  # Outputs: 42
Single and Double Underscores in Python Names

Tutorial

Single and Double Underscores in Python Names

Learn Python naming conventions with single and double underscores to design APIs, create safe classes, and prevent name clashes.

intermediate best-practices python

For additional information on related topics, take a look at the following resources:

By Leodanis Pozo Ramos • Updated Sept. 18, 2025 • Reviewed by Martin Breuss
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