# Amazon SNS topics
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Two Amazon SNS topics are created with the solution by default. One topic is to notify on all `AWSAccelerator-Pipeline` pipeline events. The second notifies only on `AWSAccelerator-Pipeline` pipeline failures. You can choose to subscribe to these topics to increase the observability of your pipeline operations. For more information, refer to [Subscribing to an Amazon SNS topic](https://docs.aws.amazon.com/sns/latest/dg/sns-create-subscribe-endpoint-to-topic.html) in the *Amazon SNS Developer Guide*.

An optional third Amazon SNS topic is created if the **EnableApprovalStage** parameter is set to `Yes` in the **AWSAccelerator-InstallerStack**. You can provide a comma-delimited list of email addresses in the **ApprovalStageNotifyEmailList** parameter to automatically subscribe to this Amazon SNS topic.