[Python] function vs class vs module vs package vs session for fixture scopes in Pytest

I set 5 fixtures with function, class, module, package and session scopes to test1() as shown below:

import pytest

@pytest.fixture(scope='function')
def fixture_function():
print('function')

@pytest.fixture(scope='class')
def fixture_class():
print('class')

@pytest.fixture(scope='module')
def fixture_module():
print('module')

@pytest.fixture(scope='package')
def fixture_package():
print('package')

@pytest.fixture(scope='session')
def fixture_session():
print('session')

class Test1:
def test1(
self,
fixture_function,
fixture_class,
fixture_module,
fixture_package,
fixture_session
):
pass


Then, I ran the command below:

pytest -q -rP


Then, each fixture ran once according to the result below:

$ pytest -q -rP
. [100%]
=============== PASSES ===============
____________ Test1.test1 _____________
_______ Captured stdout setup ________
session
package
module
class
function
1 passed in 0.10s


My questions:

1. 
   What is the difference between function, class, module, package and session for fixture scopes in Pytest?
   
   
2. 
   When should I use fixture scopes in Pytest?
   

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