diff --git a/strings.html b/strings.html
index 9ea13a6..299f9a1 100755
--- a/strings.html
+++ b/strings.html
@@ -93,7 +93,7 @@ My alphabet starts where your alphabet ends! ❞
&m
'深入 Python 3'
') or double quotes (").
-len() function returns the length of the string, i.e. the number of characters. This is the same function you use to find the length of a list. A string is like a list of characters.
+len() function returns the length of the string, i.e. the number of characters. This is the same function you use to find the length of a list, tuple, set, or dictionary. A string is like a tuple of characters.
+ operator.