if it's getting dark or its raining which lights should you use

Use your low-beam headlights—simple as that. They light the road without turning rain and spray into a blinding disco.

High beam is fine on empty roads at night, but dip within 200 m of oncoming or preceding traffic, and avoid it in rain or fog.

Fog lights are only for actual fog or heavy mist; switch them off when conditions clear, unless you enjoy fines and dirty looks.

Daytime running lights don’t activate your tail-lights, so they’re not enough when it’s dim or wet—headlights on, thanks.