diff --git a/windows/deployment/update/servicing-stack-updates.md b/windows/deployment/update/servicing-stack-updates.md
index 23321eb5ad..ef2ff43e58 100644
--- a/windows/deployment/update/servicing-stack-updates.md
+++ b/windows/deployment/update/servicing-stack-updates.md
@@ -7,7 +7,7 @@ ms.sitesec: library
 author: Jaimeo
 ms.localizationpriority: medium
 ms.author: jaimeo
-ms.date: 05/29/2018
+ms.date: 09/24/2018
 ---
 
 # Servicing stack updates
@@ -22,12 +22,20 @@ The "servicing stack" is the code that installs other operating system updates.
 
 ## Why should servicing stack updates be installed and kept up to date?
   
-Having the latest servicing stack update is a prerequisite to reliably installing the latest quality updates and feature updates. 
+Having the latest servicing stack update is a prerequisite to reliably installing the latest quality updates and feature updates. Servicing stack updates improve the reliability and performance of the update process.
 
 ## When are they released?
 
 Currently, the servicing stack update releases are aligned with the monthly quality update release date, though sometimes they are released on a separate date if required.
 
+## What's the difference between a servicing stack update and a cumulative update?
+
+Both Windows 10 and Windows Server use the cumulative update mechanism, in which many fixes are packaged into a single update. Each cumulative update includes the changes and fixes from all previous updates.
+
+However, there are some operating system fixes that aren’t included in a cumulative update but are still pre-requisites for the cumulative update. That is, the component that performs the actual updates sometimes itself requires an update. Those fixes are available in a servicing stack update. For example, the cumulative update KB4284880 requires the May 17, 2018 servicing stack update, which includes updates to Windows Update.
+
+If a given cumulative update required a servicing stack update, you'll see that information in the release notes for the update. **If you try to install the cumulative update without installing the servicing stack update, you'll get an error.**
+
 ## Is there any special guidance?
 
 Typically, the improvements are reliability, security, and performance improvements that do not require any specific special guidance. If there is any significant impact, it will be present in the release notes.