diff --git a/src/textual/widgets/_placeholder.py b/src/textual/widgets/_placeholder.py
index 138717e59..0d4c62b39 100644
--- a/src/textual/widgets/_placeholder.py
+++ b/src/textual/widgets/_placeholder.py
@@ -1,3 +1,5 @@
+"""Provides a Textual placeholder widget; useful when designing an app's layout."""
+
 from __future__ import annotations
 
 from itertools import cycle