<P> The signal can be intended to convey a variety of messages, including a warning to other drivers of road hazards, telling a driver they can pass through or alerting a driver of speed traps, and it can also be a form of aggressive driving . The legality of headlight flashing varies by jurisdiction . </P> <P> Headlight flashing might have come into more common use as a means of attempting driver - to - driver communication by the mid-1970s, when cars began to come with headlight beam selectors located on the steering column--typically activated by pulling the turn signal stalk--rather than the previous foot - operated pushbutton switches . The signal stalk configuration was later wired to permit the momentary activation of the high beams regardless of whether the headlamp switch was turned on or off . </P> <P> Headlight flashing attracts attention, and so can be considered the visual equivalent of blowing the horn . Indeed, some car owner's manuals identify headlight control on the steering column as the "optical horn". Like the horn, it has many uses . </P> <P> Headlight flashing can let other drivers know of one's presence . </P>

When may other drivers flash their headlights at you