Turn signals (US English) or indicators (British English) are a set of lights on a vehicle (be it a car, truck/lorry, tractor, motorcycle, etc.) that indicate that the driver is intending to turn.

According to the Smithsonian Institution, the turn signal was invented by Oscar J. Simler (see article at [1]) in 1929, but was not widely used on cars until 10 years later, in 1939.

Turn signals are required on all vehicles that are driven on public roadways in the United States and most other countries.

In Europe, and many other nations, turn signals are required to be an orange or amber color at both front and rear on all modern vehicles. In the United States and Canada, they may also be white at the front and red at the rear, and the same rear red lights may serve as tail lights , brake lights and turn signals.

Turn signal lights must also conform with a minimum and maximum brightness level, so that they neither are invisible nor dazzle those who view them.

Sequential turn signals

Some models of American car in the 1960s and early 1970s had multiple rear turn signal lights which flashed in a sequence, instead of all at once. These were called sequential turn signals.