Simple Notification Service

AWS Simple Notification Service (SNS) is a fully managed service, which provides a simple way to notify applications or people or various other endpoints by creating topics and using a publish-subscribe protocol. SNS allows messages to be published from within an application or directly from the console and have those messages delivered to subscribers via several protocols. Messages are first published to the centralized topics, then the subscriber to the topic receives the messages. It is used in cases where the same single messages are to be sent to many subscribers. SNS supports different protocols such as emails, HTTP, SMS, and so on.

The cost of the service is very low, and you pay only for what you use. For example, the IT production support team needs to be notified when there are issues with a production server; then CloudWatch can monitor the health, and an alarm can be raised when a specific event occurs. These alarms can be configured such that when raised, they publish a message to the SNS topic, then the subscriber to the topic will receive the message.