diff --git a/pkg/apis/core/types.go b/pkg/apis/core/types.go
index 0c6baa98332..eaea31151c3 100644
--- a/pkg/apis/core/types.go
+++ b/pkg/apis/core/types.go
@@ -4602,7 +4602,12 @@ const (
 
 // +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object
 
-// Event is a report of an event somewhere in the cluster.
+// Event is a report of an event somewhere in the cluster.  Events
+// have a limited retention time and triggers and messages may evolve
+// with time.  Event consumers should not rely on the timing of an event
+// with a given Reason reflecting a consistent underlying trigger, or the
+// continued existence of events with that Reason.  Events should be
+// treated as informative, best-effort, supplemental data.
 // TODO: Decide whether to store these separately or with the object they apply to.
 type Event struct {
 	metav1.TypeMeta
diff --git a/staging/src/k8s.io/api/core/v1/types.go b/staging/src/k8s.io/api/core/v1/types.go
index bd67349d957..11650677c34 100644
--- a/staging/src/k8s.io/api/core/v1/types.go
+++ b/staging/src/k8s.io/api/core/v1/types.go
@@ -5315,7 +5315,12 @@ const (
 // +genclient
 // +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object
 
-// Event is a report of an event somewhere in the cluster.
+// Event is a report of an event somewhere in the cluster.  Events
+// have a limited retention time and triggers and messages may evolve
+// with time.  Event consumers should not rely on the timing of an event
+// with a given Reason reflecting a consistent underlying trigger, or the
+// continued existence of events with that Reason.  Events should be
+// treated as informative, best-effort, supplemental data.
 type Event struct {
 	metav1.TypeMeta `json:",inline"`
 	// Standard object's metadata.