Typically, the fog will reflect light back to its source, which is why you end up blinded if you put your high-beams on in a fogbank. Car manufacturers have worked on lighting that is (typically) lower than the centerline of the car and sometimes tinted amber, which does a better job at penetrating the fog and reflecting back a less-blinding glare.

Some fog lights are original equipment manufacturer (OEM) items, while the majority are aftermarket fog light kits.