An AWS message queuing service that decouples components in distributed systems. Messages are stored in the queue until a consumer processes them. It supports standard queues (at-least-once) and FIFO queues (exactly-once).
Fundamental for decoupled architectures on SAA-C03. Difference from SNS: SQS is point-to-point with a buffer; SNS is immediate pub/sub. Question: avoid losing messages if a component fails → SQS.
Amazon SQS (Simple Queue Service) is a concept that can show up on the exam. Check the full guide to see it in context.