Amazon Simple Queue Service (SQS) is a fully managed message queuing service that can be used to send, store, and receive messages between software systems. Standard SQS queues provide best effort ordering, at least once delivery, and unlimited throughput. SQS FIFO queues guarantee exactly once delivery and strict ordering.
SQS queues can be used as a trigger for AWS Lambda functions and can act as a Cloudwatch event target (FIFO queues only). The SQS queue depth metric is commonly used to trigger EC2 auto-scaling activity.
Amazon SQS was the first service provided by AWS, launched in 2004 and made generally available in 2006.