diff --git a/src/pip/_internal/network/session.py b/src/pip/_internal/network/session.py
index e63fc273af4..0e9f44f562d 100644
--- a/src/pip/_internal/network/session.py
+++ b/src/pip/_internal/network/session.py
@@ -1,3 +1,6 @@
+"""PipSession and supporting code, containing all pip-specific
+network request configuration and behavior.
+"""
 import email.utils
 import json
 import logging