diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index 09f5e0542db18..017fb44413c8f 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -9471,6 +9471,14 @@ def align(
         ----------
         other : DataFrame or Series
         join : {{'outer', 'inner', 'left', 'right'}}, default 'outer'
+            Type of alignment to be performed.
+
+            * left: use only keys from left frame, preserve key order.
+            * right: use only keys from right frame, preserve key order.
+            * outer: use union of keys from both frames, sort keys lexicographically.
+            * inner: use intersection of keys from both frames,
+              preserve the order of the left keys.
+
         axis : allowed axis of the other object, default None
             Align on index (0), columns (1), or both (None).
         level : int or level name, default None