Simple Queue Service - AWS message queuing service for decoupling application components. Like a digital post office where applications can leave messages for each other.
A photo processing application uses SQS to queue image processing tasks that worker servers pick up and process.
All are managed messaging services used to decouple producers and consumers. SQS, Storage Queues, and OCI Queue are queue-centric services (point-to-point). Azure Service Bus adds richer enterprise features (sessions, transactions, dead-lettering). GCP Pub/Sub is primarily pub/sub (fan-out) but can be used for work queues via subscriptions; it differs in delivery semantics and ordering options.