Merge pull request #110605 from tfitzmac/0407benefits

update template benefits

Author: PRMerger17

articles/azure-resource-manager/templates/overview.md

@@ -2,7 +2,7 @@
 title: Templates overview
 description: Describes the benefits using Azure Resource Manager templates for deployment of resources.
 ms.topic: conceptual
-ms.date: 03/25/2020
+ms.date: 04/06/2020
 ---
 # What are ARM templates?
 
@@ -24,12 +24,18 @@ If you're trying to decide between using ARM templates and one of the other infr
 
    ![Template deployment comparison](./media/overview/template-processing.png)
 
-* **Built-in validation**: Your template is deployed only after passing validation. Resource Manager checks the template before starting the deployment to make sure the deployment will succeed. Your deployment is less likely to stop in a half-finished state.
-
 * **Modular files**: You can break your templates into smaller, reusable components and link them together at deployment time. You can also nest one template inside another templates.
 
 * **Create any Azure resource**: You can immediately use new Azure services and features in templates. As soon as a resource provider introduces new resources, you can deploy those resources through templates. You don't have to wait for tools or modules to be updated before using the new services.
 
+* **Extensibility**: With [deployment scripts](deployment-script-template.md), you can add PowerShell or Bash scripts to your templates. The deployment scripts extend your ability to set up resources during deployment. A script can be included in the template, or stored in an external source and referenced in the template. Deployment scripts give you the ability to complete your end-to-end environment setup in a single ARM template.
+
+* **Testing**: You can make sure your template follows recommended guidelines by testing it with the ARM template tool kit (arm-ttk). This test kit is a PowerShell script that you can download from [GitHub](https://github.com/Azure/arm-ttk). The tool kit makes it easier for you to develop expertise using the template language.
+
+* **Preview changes**: You can use the [what-if operation](template-deploy-what-if.md) to get a preview of changes before deploying the template. With what-if, you see which resources will be created, updated, or deleted, and any resource properties that will change. The what-if operation checks the current state of your environment and eliminates the need to manage state.
+
+* **Built-in validation**: Your template is deployed only after passing validation. Resource Manager checks the template before starting the deployment to make sure the deployment will succeed. Your deployment is less likely to stop in a half-finished state.
+
 * **Tracked deployments**: In the Azure portal, you can review the deployment history and get information about the template deployment. You can see the template that was deployed, the parameter values passed in, and any output values. Other infrastructure as code services aren't tracked through the portal.
 
    ![Deployment history](./media/overview/deployment-history.png)