Queue
also: queues, queued, message queue, job queue
A waiting line for tasks. One part of your app adds tasks to the line, and another part takes them off and handles them in order.
A service or data structure (BullMQ on Redis, Amazon SQS, RabbitMQ) that stores jobs or messages until a consumer processes them, usually first in, first out. Queues separate the code that creates work from the code that does it, absorb spikes, and allow retries.
The ticket rail in a busy kitchen. Waiters clip orders on; cooks take them off one by one. Waiters don't wait for each dish to be cooked before taking the next order.
When an agent suggests "putting it on a queue", the work will happen later, not instantly. That changes what users see, and you need a plan for tasks that fail.
I'll push each image-resize request onto a queue, so the upload returns immediately and resizing happens in the background.
If we add a queue for sending receipts, what happens when a send fails? Make failed jobs retry a few times, then log them. Don't drop them silently.
Thinking the queue does the work. The queue only holds tasks. A separate worker takes them off the queue and does them.