conftest
The conftest.py file serves as a means of providing fixtures for an entire directory. Fixtures defined in a conftest.py can be used by any test in that package without needing to import them (pytest will automatically discover them).
You can have multiple nested directories/packages containing your tests, and each directory can have its own conftest.py with its own fixtures, adding on to the ones provided by the conftest.py files in parent directories.
parametrization
The builtin pytest.mark.parametrize decorator enables parametrization of arguments for a test function.
Custom command line parameters
Shyshkin Dmitry. Selenium WebDriver: Selenium Automation Testing with Python. Udemy