diff --git a/docs/docsite/rst/reference_appendices/common_return_values.rst b/docs/docsite/rst/reference_appendices/common_return_values.rst
index 2749526550a..bca1ef970ad 100644
--- a/docs/docsite/rst/reference_appendices/common_return_values.rst
+++ b/docs/docsite/rst/reference_appendices/common_return_values.rst
@@ -24,6 +24,11 @@ changed
 ```````
 A boolean indicating if the task had to make changes.
 
+diff
+````
+
+Information on differences between the previous and current state. Often a dictionary with entries ``before`` and ``after``, which will then be formatted by the callback plugin to a diff view.
+
 failed
 ``````
 A boolean that indicates if the task was failed or not.