We’ve all had it happen: You look in the mirror and the car behind you looks like it is right in your back seat. That driver tailgates you mercilessly down the highway. If you speed up, the other car stays right where it is. If you slow down, it just gets closer.

Why do people do it? It’s incredibly dangerous. It causes accidents. It offers no benefits. It eliminates reaction times.

While it may not make sense to you, and it is illegal, here are five reasons why some people choose to tailgate:

1. They’re impatient

They want to get there five minutes ago. You’re slowing them down. They feel like tailgating you will either make you speed up or cause you to pull over and get out of the way. Never mind the danger or the fact that most drivers do not do either thing when tailgated. They keep doing it, seething at the “slow” speed.

2. They’re angry

In many cases, road rage leads to tailgating. Maybe you accidentally pulled out in front of that other car. That driver decides to tailgate you to get back at you and show you what you did wrong. This can escalate into road rage in some situations.

3. They’re young

Experts suggest that all drivers stay about two seconds behind the next vehicle. Anything less is considered dangerous. However, studies have found that young, inexperienced drivers break this rule more often than older drivers. It could be that young drivers are reckless, or they may simply not have the experience to recognize the proper following distance.

4. They’re ignorant

Strange as it may sound while you stare at those headlights in the mirror, some drivers honestly do not know how dangerous tailgating is. Others do not know what a safe following distance really looks like. A diver may honestly think that he or she is driving in a safe, controlled manner, when that driver looks reckless and negligent to you.

5. They’re drafting

This is uncommon, but some drivers mistakenly think driving close to the next car helps them “draft” and reduces the amount of gas they burn by reducing wind resistance. This is real. It works in stock car racing, when even the smallest amount of speed or fuel economy makes a huge difference. In a normal passenger car, though, it does almost nothing. Unfortunately, that does not stop uninformed drivers from trying.

Accidents and injuries

If a tailgating driver hits you, it can lead to severe injuries. You may not have any way to avoid the accident. If you wind up in the hospital with rising medical bills, make sure you know what legal options you have to seek compensation.