"Amazon Simple Queue Service is the glue that holds it all together. This is by far the most important service, and Jay is surprised that he doesn’t hear more about it from the development community. He uses it for job control, synchronization and general impedance matching. I agree with Jay: I frequently refer to Amazon SQS as an impedance transformer, or sometimes as a “transmogrifier”, because it eliminates dependencies on the other component in a loosely-coupled system. And in a true loosely-coupled system you never know what the other end point looks like, or if it is even in operation at any given moment."

— Amazon Web Services blog