Fog lights, or fog lamps, are small, block- or round-shaped lights located beneath the headlights on the front of your car. They are angled in a particular way so that the light directly illuminates the road ahead of you instead of several feet off the ground as regular headlights do.
Front fog lamps are for use during poor weather situations where visibility is reduced, like in misty, rainy, foggy, or dusty weather. Since headlights can be too bright in low visibility situations and reflect into the driver’s eyes, fog lights are safer and more preferred by many drivers.
If your car doesn’t have fog lights, then that might be the new normal. Not every car has fog lights because they only fit specific makes and models. In fact, fewer cars than ever before have fog lights because newer models are forgoing them altogether. But the phasing out of fog lights is only applicable to the front: Rear fog lights are still a requirement in many states and are seen as necessary for sharing the road with other drivers.
Although it may look like it, fog doesn’t actually touch the ground, so fog lights are angled to be as close to the ground as possible. The lights are turned sharply downwards so that only the actual ground ahead of you is lit up, which also helps prevent blinding you (and other drivers).
When changing your front fog lamp bulb, a yellow light bulb is most common. White lights tend to create a glare against rain and snow, which can be confusing, blinding, and dangerous. On the other hand, yellow lights can pierce through the low visibility without glare, making it a softer drive on the eyes.
Frontal fog lights are designed to help you see the ground better in low visibility circumstances. Similarly, rear fog lights (or rear fog lamps) are there to help other drivers behind you avoid hitting you. Rear fog lights help with interpreting distance and serve as an extra set of low-level lights for other drivers to see.
Since fog lights are dim and aimed downwards, there’s no use for them unless visibility is an issue. They’re only necessary when the weather is terrible or it’s hard to see the road in front of you, meaning that you should reserve them for dangerous driving conditions, such as: Rain, Snow, Fog, Mist, Dust.