Message Queue
Also written as RabbitMQ, SQS
A system that lets different parts of an application send tasks or events to each other asynchronously, improving reliability and decoupling services.
Think of it like
Like a restaurant's order-ticket rail — the waiter drops off an order and moves on, and the kitchen works through tickets at its own pace instead of the waiter standing there waiting.
Junior or senior?
Junior sounds like
Hasn't hit a scale where synchronous calls stopped being enough.
Senior sounds like
Can describe the specific problem that led their team to introduce a message queue instead.
Ask them
“What problem led your team to introduce a message queue instead of calling services directly?”
Sounds like real experience
Names the specific breaking point — a synchronous call chain that couldn't handle load, a service that needed to keep working while another was down — that made a queue necessary.
Probe further if
Names a queue technology without describing the actual problem it solved, or credits the queue itself for reliability without describing what they had to design around it (retries, ordering, duplicates).