What is the difference between a module and a package?

Q: What is the difference between a module and a package?

**Target Audience:** Beginners learning Python, and anyone preparing for a Python interview **Difficulty:** Easy **Python version:** Every example was run on CPython 3.11 (and in this page on Pyodide 0.25.1, which is CPython 3.11.3) > **How to read this doc:** Each idea is explained in plain language first, then tagged with `📌 Interview term:` so you also learn the exact word an interviewer expects. Every output block in the **Verified** section was copied from a real run of the examples on this page. ## 1. Why This Even Matters — A Story First Think of a kitchen. A single recipe card ("Tomato soup") is useful on its own: you pick it up and follow it. That is a **module**. A recipe **binder** with tabs ("Soups", "Desserts", and inside "Desserts" another tab for "Cakes") is how you keep fifty cards findable. That is a **package**. The binder also has a cover page that says "start here: the three recipes most people want". That cover page is `__init__.py`. As soon as a program grows

The problem

Question presented to candidate: "In Python, what is the difference between a module and a package? How does Python know a folder is a package, what does __init__.py do, and is it still required?"

What a strong answer should cover:

A module is the unit of import: usually one .py file, loaded into a module object whose attributes are the file's top-level names
A package is a module that can contain other modules: it has a __path__ attribute (the folders searched for its submodules), and its own code lives in __init__.py
At run time both are the same type (types.ModuleType); "package" just means "has __path__", and dotted names like shop.payments.card walk down packages
__init__.py runs once on first import and is where a package exposes its public API (re-exports, __all__); importing a package does not import all its submodules
Namespace packages (PEP 420, Python 3.3+) have no __init__.py, can be split over several folders, and have __file__ = None; a regular package with __init__.py wins over namespace portions
Modules and packages are code-organisation units; a distribution (what pip install downloads) is a different thing that can ship many of them

Code / implementation expected: Optional — sketch a small folder layout and show import pkg.sub and from pkg import name.

modules
packages

Try it yourself

Sketch your approach before you read the solution. That is what the interview tests.

Stuck? Get a hint.

A short nudge toward the approach. It will not give the answer away.

Solution

Target Audience: Beginners learning Python, and anyone preparing for a Python interview Difficulty: Easy Python version: Every example was run on CPython 3.11 (and in this page on Pyodide 0.25.1, which is CPython 3.11.3)

How to read this doc: Each idea is explained in plain language first, then tagged with 📌 Interview term: so you also learn the exact word an interviewer expects. Every output block in the Verified section was copied from a real run of the examples on this page.

1. Why This Even Matters — A Story First

Think of a kitchen. A single recipe card ("Tomato soup") is useful on its own: you pick it up and follow it. That is a module. A recipe binder with tabs ("Soups", "Desserts", and inside "Desserts" another tab for "Cakes") is how you keep fifty cards findable. That is a package. The binder also has a cover page that says "start here

The solution is hidden so you can try first

12 min read · 12 sections

Run the code

Edit the code and run it here. Each console line with an expected value becomes a test.

PythonBuild a module and a package on disk, then import them

Practice

PythonNamespace packages, which package wins, and __all__

Practice

Discussion

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