A traffic light is a device used to control movements at an intersection or at-grade crossing between two roads. Standard signals use three lens orientated from top to bottom or left to right with red, amber and green. Signals vary in housing styles based upon manufacturer and color schemes from state to state, and in municipalities throughout the country.
Variations of signals include the five-lens doghouse signal with left or right turn arrows, the four or five signal stacked signals, with amber and yellow turn arrows at the bottom, and upside down T signals with a green arrow positioned along side a green ball lens.

Backplates are added to signals to add visibility against the sky or background. Visors vary between full tunnel or cutout assemblies.