diff --git a/pandas/tests/plotting/common.py b/pandas/tests/plotting/common.py
index c868c8d4fba07..1f94e18d8e622 100644
--- a/pandas/tests/plotting/common.py
+++ b/pandas/tests/plotting/common.py
@@ -1,3 +1,10 @@
+"""
+Module consolidating common testing functions for checking plotting.
+
+Currently all plotting tests are marked as slow via
+``pytestmark = pytest.mark.slow`` at the module level.
+"""
+
 import os
 from typing import TYPE_CHECKING, Sequence, Union
 import warnings