Bottlenecks
Have you ever been stuck in a traffic jam? A big one, like on a major highway that runs through a large city. You know the good ones where you are parked on the highway next to the speed limit sign that mocks you with the limit of 70 miles per hour. If you make progress at all its only inches or if your really lucky, feet at a time. \n\n\tThen all of a sudden you get past whatever the cause was, the major off-ramp, the accident or toll booth/bridge, and the traffic all of a sudden parts like Moses and the Red Sea and your free, quickly forgetting the stress and frustration of the mess behind you. You have just experienced a bottleneck.