Message Queue

A component that stores messages or tasks in an ordered buffer, allowing different parts of a system to communicate asynchronously by decoupling the sender from the receiver so neither needs to wait for the other.

Message queues prevent system overload during traffic spikes by absorbing bursts of activity that the processing system can handle at its own pace. They also ensure no work is lost if a downstream service temporarily fails.

A founder's platform sends confirmation emails after every purchase. Rather than sending directly during checkout (which would slow the payment response), the checkout service drops a message into a queue. A separate email service processes messages at its own rate, keeping checkout fast even during peak traffic.