diff --git a/docs/modules/pickle.md b/docs/modules/pickle.md
index 64474bb3..d243e052 100644
--- a/docs/modules/pickle.md
+++ b/docs/modules/pickle.md
@@ -11,3 +11,15 @@ Return the pickled representation of an object as a bytes object.
 
 Return the unpickled object from a bytes object.
 
+
+## What can be pickled and unpickled?
+
+The following types can be pickled:
+
+- [x] None, True, and False;
+- [x] integers, floating-point numbers;
+- [x] strings, bytes;
+- [x] tuples, lists, sets, and dictionaries containing only picklable objects;
+- [ ] functions (built-in and user-defined) accessible from the top level of a module (using def, not lambda);
+- [ ] classes accessible from the top level of a module;
+- [x] instances of such classes