Setuptools
Setuptools is a Python library and command-line tool for building and distributing Python packages, particularly as source distributions (sdist) and wheels. It extends Python's standard distutils by providing features like automatic dependency resolution, entry point support for creating console scripts, and integration with package indexes like PyPI. It is the de facto standard for packaging Python projects and is used by tools like pip for installation.
Developers should learn Setuptools when creating Python libraries or applications that need to be shared, installed via pip, or published to PyPI, as it simplifies packaging, dependency management, and distribution. It is essential for projects requiring complex metadata, custom build steps, or plugin architectures, such as web frameworks like Django or data science tools like Pandas. Using Setuptools ensures compatibility with the broader Python ecosystem and tools like virtual environments.