Tailgating is a term referred to when a motorist follows the vehicle in front of them too closely. This poses several problems and promotes bad driving habits. Following a vehicle too close blocks the motorist's view ahead, which can be dangerous. If the vehicle in front has to stop suddenly for a hazard, that leaves little-to-no time to react, which can result in a rear-end collision.
Following Too Closely
21703 of the California Vehicle Code states that the driver of a motor vehicle shall not follow another vehicle more closely than is reasonable and prudent, having due regard for the speed of such vehicle and the traffic upon, and the condition of, the roadway.
The 2005 California Drivers Handbook recommends the "Three Second Rule." When the vehicle ahead of you passes a certain object, i.e. traffic signal pole etc., count one-thousand-one, one-thousand-two, one-thousand-three. This should only be about three seconds. If you should pass the same object before you have finished counting, you are following too close to the vehicle in front of you.