Tailgating is the practice of driving on a road too closely to other vehicles, which does not guarantee to avoid collision. A person who considers themselves safe drivers and generally obeys the other rules of the road does it unconsciously or negligently, very often. Approximately one third of rear-end collisions involve tailgating. It can be a particularly virulent form of road rage and a form of intimidation. The driver being tailgated might not wish to comply, especially if doing so would involve breaking the law, such as by increasing speed beyond the speed limit or changing lanes without due regard for safety.

Tailgating can also be dangerous to the tailgater, especially if he or she is driving closely behind a heavy vehicle. If the leading vehicle decelerates suddenly, the tailgater has a high risk of causing a rear-end collision. A driver may switch into a lane in front of another driver, but without adequate clearance. A driver is driving slower than the flow of traffic while in one of the faster lanes of a multi-lane road.

A faster driver approaching from behind wishing to overtake may tailgate to indicate this desire to the slower driver in front and attempt to make him change lanes. A driver traveling at a higher speed reaches a car traveling in the same direction at a lower speed, and the faster driver may tailgate while awaiting the first opportunity to overtake. Such expressions of impatience may be conscious or unconscious, and dangerous.