When driving, it is impossible to communicate verbally with other drivers who are also in their own cars, separated from you.
For this reason, a whole lexicon of communication has emerged that uses hand signals to convey specific meanings.
While not a formal sign language, hand signals are one of the largest sets of gestures.
Although driving hand signals differ from country to country, many are universal, at least within a region like Europe or North America.
The most basic hand signals are those used to show that you are about to turn. These signals are used if you are in a car or truck that has broken turn signals, or if you are in a vehicle such as a bicycle that does not have turn signals to start. In the United States and other right-hand drive countries, the left hand is used, as the driver is on the left side of the vehicle, so this allows them to stick their arm out the window.
In countries that drive on the left side of the road, the right hand is used. The arm set all the way out, at a right angle, indicates preparing to turn in that direction: left in America, right in a place like Britain. The arm that is positioned with the forearm pointing upward with the elbow at a ninety-degree angle indicates that it is preparing to turn in the opposite direction: right in America, left in a place like Britain. The extended arm with the forearm pointing down with the elbow at a ninety degree angle indicates a halt.
Besides turning, there are a number of other important things that can be communicated to other drivers through the use of hand signals. For example, pointing out the window and down onto the road with a fully extended index finger indicates that the approaching driver should be aware of an obstacle in the road. Placing the palm of the hand down and pushing it down slowly is a sign that the oncoming driver should slow down. Placing the palm of the open hand directly toward the oncoming driver indicates that the driver should stop. And moving your hand with your palm to one side from side to side indicates that the car in front should stop.
Other hand signals are more conversational, both in this country and in other countries. For example, the shaka symbol, with the thumb and little fingers extended from a clenched fist, is often used as a symbol of appreciation, for example, to drivers who have let you pass. The same symbol in some parts of Europe is used as recognition by Volkswagen drivers to other Volkswagen drivers, as it creates a V and W with just one hand. The V hand signal, often associated with the symbol of victory or peace, serves a similar function in Australia, where it is used when passing a valiant charger.
Of course, there is also another set of manual driving signals, which are mainly used to show disappointment or anger towards another driver.
These symbols, from a single digit up, to a thumb against the teeth, are the same angry gestures widely used in their respective cultures.