diff --git a/data-transform.qmd b/data-transform.qmd
index 011acdd..1b939b9 100644
--- a/data-transform.qmd
+++ b/data-transform.qmd
@@ -420,6 +420,7 @@ flights |>
 
 `group_by()` doesn't change the data but, if you look closely at the output, you'll notice that it's now "grouped by" month.
 This means subsequent operations will now work "by month".
+`group_by()` doesn't do anything by itself; instead it changes the behavior of the subsequent verbs.
 
 ### `summarize()` {#sec-summarize}