This figure uses two timelines in order to illustrate the FIFO queue. Both timelines are horizontal and run from left to right; one is labeled "Arrivals," and the other, below it, is labeled "Departures." Between them is a series of five numbered packets, designated as "Packet in service." Packets 1-4 are equally spaced, and then there is a small gap, followed by packet 5. Each timeline has hash marks at regular intervals, however only in the bottom timeline, "Departures," are these hash marks labeled. The first is labeled "t = 0," the second is unlabeled, the third is labeled "t = 2," and so on in this pattern up to "t = 14."

In the arrivals timeline, packet 1 appears on the first hash mark. Packet 2 appears between the second and third hash mark, packet 3 appears between the third and fourth hash mark. Packet 4 appears just after the eighth hash mark, and packet 5 appears at the fourteenth hash mark. In the departures timeline, packet 1 appears at t = 3, packet 2 appears at t = 6, packet 3 appears at t = 9, packet 4 appears at t = 12, and packet 5 appears two hash marks beyond t = 14.