diff --git a/engine/swarm/key-concepts.md b/engine/swarm/key-concepts.md
index 1c2c875863..200e35e62a 100644
--- a/engine/swarm/key-concepts.md
+++ b/engine/swarm/key-concepts.md
@@ -44,7 +44,7 @@ worker.
 
 ## Services and tasks
 
-A **service** is the definition of the tasks to execute on the worker nodes. It
+A **service** is the definition of the tasks to execute on the manager or worker nodes. It
 is the central structure of the swarm system and the primary root of user
 interaction with the swarm.