Answer
__init__.py marks a directory as a regular Python package and initializes that package. • Its code runs when the package is first imported. • It can define package-level names and __all__. • Namespace packages can exist without this file.
💡 Simple Example
# package/__init__.py
__all__ = ['helpers']
⚡ Quick Revision
__init__.py initializes a regular package; namespace packages may omit it.