Turning

Vehicles will often want to cease to travel in a straight line and turn onto another road. The vehicle's directional signals (blinkers) are often used as a way to announce one's intention to turn, thus alerting other drivers. The actual usage of blinkers varies greatly amongst countries. Turning traffic must usually yield the right of way to oncoming traffic - in right-driving countries, vehicles must yield when performing a left turn; on left-driving countries vehicles must yield when performing a right turn.

Source: http://en.wikipedia.org/wiki/Rules_of_the_road