Your fog lights have been fitted to your car for use in fog and heavy mist which significantly reduces visibility on the road.
Specifically, they're meant to be used when visibility drops below 100m, around the length of a football pitch.
At this point, you should be driving slowly enough to react to hazards, remembering your stopping distances.
If you don't switch on your headlights under these conditions you could risk the safety of yourself or other road users.
If you are involved in an accident during fog and you don't have your fog lights on it could mean that your insurance is invalid.
According to the RAC, you should: "Use your common sense. If the fog is so severe that you’re struggling to see other vehicles, switch on your fog lights.
''But don’t keep switching them off and on again, as this can confuse other drivers."
If you use your fog lights when it isn't foggy you could be endangering other road users and potentially breaking the law.
You should never use your fog lights in rain or drizzle - and could be fined by the police if caught.
The Road Vehicles Lighting Regulations 1989 says that it is illegal to use your lights to dazzle drivers coming towards you.
Fog lights are very bright, which means they shouldn't be used in normal weather.
Switching or leaving your fog lights on when it's clear, or if it's just rainy, or in light mist where visibility is greater than 100m, could land you with a fine.
If you use your fog lights incorrectly, you could be fined £30 at the roadside.
You won't get penalty points if dealt with in this way.
If you cause an accident or injure somebody, the penalties could be much harsher and include points, bigger fines and even a ban.
Every car is different, so you'll need to check your manual to be sure you know how to switch on your fog lights.
But in general, you would start by switching on your headlights as normal.
Then locate the fog light symbol - which may be on the indicator stalk with the other light functions.
You may have to rotate the end of the stalk, or flick a switch to the right or left of the steering wheel.
Alternatively, it could be a button to press on your dashboard.
Whatever the method, you should familiarise yourself with how to turn the lights on before you go out in more weather.
You also need to make sure you remember to turn them off again when they are no longer necessary.
