diff --git a/html_sanitizer.rst b/html_sanitizer.rst
index f2400103284..b2b7a2cbee7 100644
--- a/html_sanitizer.rst
+++ b/html_sanitizer.rst
@@ -462,6 +462,80 @@ This can also be used to remove elements from the allow list.
->dropElement('figure')
);
+Default Action
+~~~~~~~~~~~~~~
+
+By default, unconfigured tags are dropped along with their children. If you would rather not lose all children elements by default, you can configure the default action to be ``Block``. Specific elements can still be dropped if needed.
+
+ .. code-block:: yaml
+
+ # config/packages/html_sanitizer.yaml
+ framework:
+ html_sanitizer:
+ sanitizers:
+ app.post_sanitizer:
+ # ...
+
+ # remove all tags by default, but process their children
+ default_action: 'block'
+ # remove