Other forms: headlights
If you’re driving a car at night, you’re using your car’s headlights to light up the road in front of you. Headlights are the eyes of a car or train, beaming light to help you see what is ahead.
The headlight is an important part of an automobile, and without it you could only drive at night where there are lots of street lights. On unlit roads, a deer might jump in front of your car and just stand there — staring into the light from your headlights. That’s where the expression “like a deer in headlights” comes from, and it means being really still after a shock, like you’re frozen in place.