A queue is a waiting line. You add items at the back and remove them from the front. Nobody jumps ahead; the order you arrive is the order you leave.
FIFO means first in, first out. The item that waited longest gets served next. A ticket counter works this way. The person at the front, who came earliest, is called first.
This fairness makes queues natural for scheduling and buffering. Print jobs, task runners, and message pipelines process work in arrival order. When order and fairness matter more than recency, a queue fits. It keeps the oldest waiting item from starving behind newer arrivals.
Rewriting in plainer words…
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