Merge pull request #189579 from spelluru/EHubdefaultAction0223

Supports Cloud events schema too

Author: hmacgregor1

articles/event-grid/custom-topics.md

@@ -2,7 +2,7 @@
 title: Custom topics in Azure Event Grid
 description: Describes custom topics in Azure Event Grid. 
 ms.topic: conceptual
-ms.date: 07/27/2021
+ms.date: 02/23/2022
 ---
 
 # Custom topics in Azure Event Grid
@@ -13,7 +13,11 @@ An event grid topic provides an endpoint where the source sends events. The publ
 When designing your application, you have flexibility when deciding how many topics to create. For large solutions, create a **custom topic** for **each category of related events**. For example, consider an application that sends events related to modifying user accounts and processing orders. It's unlikely any event handler wants both categories of events. Create two custom topics and let event handlers subscribe to the one that interests them. For small solutions, you might prefer to send all events to a single topic. Event subscribers can filter for the event types they want.
 
 ## Event schema
-For a detailed overview of event schema, see [Azure Event Grid event schema](event-schema.md). For custom topics, the event publisher determines the **data** object. The top-level data should have the same fields as standard resource-defined events.
+Azure Event Grid supports two types of event schemas: Event Grid event schema and Cloud event schema. 
+
+### Event Grid event schema
+
+When you use Event Grid event schema, you can specify your application-specific properties in the **data** object. 
 
 ```json
 [
@@ -32,8 +36,18 @@ For a detailed overview of event schema, see [Azure Event Grid event schema](eve
 ]
 ```
 
-The following sections provide links to tutorials to create custom topics using Azure portal, CLI, PowerShell, and Azure Resource Manager (ARM) templates. 
+> [!NOTE]
+> For more information, see [Event Grid event schema](event-schema.md).
+
+### Cloud event schema
+In addition to its [default event schema](event-schema.md), Azure Event Grid natively supports events in the [JSON implementation of CloudEvents v1.0](https://github.com/cloudevents/spec/blob/v1.0/json-format.md) and [HTTP protocol binding](https://github.com/cloudevents/spec/blob/v1.0/http-protocol-binding.md). [CloudEvents](https://cloudevents.io/) is an [open specification](https://github.com/cloudevents/spec/blob/v1.0/spec.md) for describing event data.
 
+CloudEvents simplifies interoperability by providing a common event schema for publishing, and consuming cloud based events. This schema allows for uniform tooling, standard ways of routing & handling events, and universal ways of deserializing the outer event schema. With a common schema, you can more easily integrate work across platforms.
+
+> [!NOTE]
+> For more information, see [Cloud event schema](cloud-event-schema.md).
+
+The following sections provide links to tutorials to create custom topics using Azure portal, CLI, PowerShell, and Azure Resource Manager (ARM) templates. 
 
 ## Azure portal tutorials
 |Title  |Description  |