The Key purpose for these type of service how different services or microservices communicate with one another.

It enables:

1. Decoupling Services (so they can work independently
2. Message queuing and delivery
3. Coordination between tasks

Simple Notification Service (SNS)

A fully managed messaging service that enables the delivery of messages, notifications, and alerts to a distributed set of recipients via multiple communication protocols.

Simple Queue Service (SQS)

A fully managed message queuing service that allows decoupling and asynchronous communication between distributed software components, enabling scalable and reliable application architectures.

EventBridge

A serverless event bus service that makes it easy to connect and automate workflows across various AWS services and third-party applications.