Merge branch 'master' into release-1.12

content/en/docs/reference/glossary/aggregation-layer.md

@@ -0,0 +1,20 @@
+---
+title: Aggregation Layer
+id: aggregation-layer
+date: 2018-10-08
+full_link: /docs/concepts/extend-kubernetes/api-extension/apiserver-aggregation/
+short_description: >
+  The aggregation layer lets you install additional Kubernetes-style APIs in your cluster.
+
+aka: 
+tags:
+- architecture
+- extension
+- operation
+---
+ The aggregation layer lets you install additional Kubernetes-style APIs in your cluster.
+
+<!--more--> 
+
+When you've configured the {{< glossary_tooltip text="Kubernetes API Server" term_id="kube-apiserver" >}} to [support additional APIs](https://kubernetes.io/docs/tasks/access-kubernetes-api/configure-aggregation-layer/), you can add `APIService` objects to "claim" a URL path in the Kubernetes API.
+