diff --git a/backend/doc.go b/backend/doc.go
index e85cef355..f82c3d671 100644
--- a/backend/doc.go
+++ b/backend/doc.go
@@ -1,2 +1,5 @@
 // Package backend provides local and remote storage for restic repositories.
+// All backends need to implement the Backend interface. There is a
+// MockBackend, which can be used for mocking in tests, and a MemBackend, which
+// stores all data in a hash internally.
 package backend