--- title: Python Modules and Packages – An Introduction – Real Python description: Python modules and packages let you break large programs into smaller, reusable pieces. A module is any `.py` file; Python finds it by searching `sys.path`,... canonical: https://daily.dev/posts/python-modules-and-packages-an-introduction-real-python-trpja5ltz twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Python Modules and Packages – An Introduction – Real Python | daily.dev og:description: Python modules and packages let you break large programs into smaller, reusable pieces. A module is any `.py` file; Python finds it by searching `sys.path`,... og:url: https://daily.dev/posts/python-modules-and-packages-an-introduction-real-python-trpja5ltz og:image: https://api.daily.dev/og/posts/trPja5lTZ.png og:image:alt: Python Modules and Packages – An Introduction – Real Python og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Python Modules and Packages – An Introduction – Real Python **[Real Python](https://daily.dev/sources/rpython)** · 24 min read · 0 upvotes · 0 comments ## Summary Python modules and packages let you break large programs into smaller, reusable pieces. A module is any `.py` file; Python finds it by searching `sys.path`, built from the script directory, the `PYTHONPATH` variable, and installation-dependent paths. The `import` statement has several forms, including `import x`, `from x import y`, and aliasing with `as`. Packages group modules using directory structure and dot notation, and since Python 3.3 no longer require an `__init__.py` file thanks to implicit namespace packages. An `__all__` list in `__init__.py` controls what `from package import *` imports, and `..` enables relative imports between sibling subpackages. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### Do I still need an __init__.py file to create a package in Python 3? No, Python does not require an __init__.py file to define a package. Starting with Python 3.3, Implicit Namespace Packages were introduced, letting the operating system's directory structure alone define a package. An __init__.py can still be included if you need package initialization code, but it is optional. _Developers structuring new Python projects can find similar packaging clarifications on daily.dev._ ### Why does from module import * not bring in everything when I import a package with import *? For a package, from import * imports nothing by default unless the package's __init__.py defines a list named __all__ listing the module names to import. This differs from a plain module, where import * imports every name not starting with an underscore when __all__ is absent. _Anyone debugging unexpected import behavior can track these Python import quirks on daily.dev._ ### How do I import a function from a sibling subpackage using a relative import in Python? Use dot notation where a single dot refers to the current package and two dots refer to the parent package, for example 'from ..sub_pkg1.mod1 import foo' inside a module in sub_pkg2. This relative import resolves sub_pkg1 as a subpackage of the shared parent package, letting modules in sibling subpackages reference each other's functionality. _Developers organizing multi-package Python codebases can revisit import patterns like this on daily.dev._ ## Similar posts on daily.dev - [.py Do? – Real Python](https://daily.dev/posts/py-do-real-python-f87ns34ep) · Real Python · 0 upvotes · 0 comments - [: Packages, Modules, and Wildcard Imports Quiz – Real Python](https://daily.dev/posts/packages-modules-and-wildcard-imports-quiz-real-python-ahhafnalg) · Real Python · 1 upvotes · 0 comments --- Tags: [#python](https://daily.dev/tags/python) [View this post on daily.dev](https://daily.dev/posts/python-modules-and-packages-an-introduction-real-python-trpja5ltz) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Python Modules and Packages – An Introduction – Real Python","url":"https://daily.dev/posts/python-modules-and-packages-an-introduction-real-python-trpja5ltz","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/python-modules-and-packages-an-introduction-real-python-trpja5ltz"},"datePublished":"2026-10-25T14:16:25.665Z","dateModified":"2026-10-25T14:17:06.128Z","description":"Python modules and packages let you break large programs into smaller, reusable pieces. 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