SQS is a managed message queue. It sits between parts of your app so they don’t have to talk directly — one component drops messages in the queue, another pulls them out and processes them at its own pace. This decoupling is what keeps systems resilient under load.
Standard vs FIFO, and why it matters
Standard queues give massive throughput but only best-effort ordering and at-least-once delivery (a message can arrive twice). FIFO queues guarantee exact order and exactly-once processing, at lower throughput. If a question stresses strict ordering or no duplicates, it’s FIFO.
Test yourself
An order-processing system must handle messages in the exact order received, with no duplicates. Which queue type?
- SQS Standard queue
- SQS FIFO queue
- SNS topic
- Kinesis Data Firehose
👉 Click to reveal the answer & explanation
Correct answer: B. FIFO queues guarantee ordering and exactly-once processing — exactly what strict order and no duplicates require. Standard (A) is best-effort ordering with possible duplicates; SNS (C) is pub/sub, not a queue; Firehose (D) is streaming delivery.
Related topics
Amazon SNS · AWS Lambda · Kinesis Data Streams
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