Traffic light

Traffic lights (or traffic signals or stoplights) are lights used to control the movement of traffic. They are placed at road intersections and crossings.^[1] The different colours of lights tell drivers what to do.

This diagram shows how a traditional traffic light works.
Picture 1: A red light means stop.
Picture 2: A green light means go.
Picture 3: A yellow light means slow down and be ready to stop.

In South Africa, they call them robots.^[2][3]

In Japan, the green light is also blue because ao in Japanese means green and blue.^[4]

Light cycles

Traffic lights change their colours in the same order every time. In most English-speaking countries, traffic lights usually change in this order:

1. Red light on: This tells drivers to stop.
2. Green light on: This tells drivers to start or keep driving.
3. Yellow light on: This tells drivers to drive slowly.

Lester Wire was credited with the invention of the electric traffic light in 1912 in Salt Lake City, Utah.^[5] Garrett Morgan, an African-American inventor, also developed a traffic signalling system, and was one of the first people to get a patent for a traffic light.^[6]

William Potts, a Detroit police officer, invented the first traffic light with three colours in 1920 in Detroit, Michigan.^[7]