diff --git a/specification/modules/search.rst b/specification/modules/search.rst
index d6bfd391..9fee097c 100644
--- a/specification/modules/search.rst
+++ b/specification/modules/search.rst
@@ -10,6 +10,13 @@ Client behaviour
 ----------------
 {{search_http_api}}
 
+Search Categories
+~~~~~~~~~~~~~~~~~
+
+The search API allows clients to search in different categories of items.
+Currently, the only specified category is ``room_events``, which searches for
+events in rooms the user had joined.
+
 Security considerations
 -----------------------
 The server must only return results that the user has permission to see.