Simple Notification Service - highly available, secure, Public service but VPC can access if has a public endpoint.
Regional Resilient.
Coordinates sending and delivery of messages ⇐ 256 KB payloads (delivery can be filtered)
SNS Topic, base entry, define permissions and configuration
Publisher - sends messages to the topic
Subscribers - receive messages, can be: HTTP(s), SQS (Fanout Architecture), Email(-json), Mobile push, SMS Messages & Lambda
Used across AWS for notifications like: CloudWatch (Metrics) & CloudFormation.
Delivers
Delivery Status - (for HTTP, SQS, Lambda..)
Delivery Retries - Reliable Delivery
HA & Scaleable - Regional
Server Side Encryption (SSE) - needed to have if mandated by requirements
Cross-Account via Topic policy