As an example of jitter, consider two consecutive packets in our VoIP application. The sender sends the second packet 50 msecs after sending the first packet. But at the receiver, the spacing between these packets can become greater than 50 msecs. To see this, suppose the first packet arrives at a nearly empty queue at a router, but just before the second packet arrives at the queue a large number of packets from other sources arrive at the same queue. Because the first packet experiences a small queuing delay and the second packet suffers a large queuing delay at this router, the first and second packets become spaced by more than 50 msecs.

The question is: Give an analogy with driving cars on roads.