Turn-by-turn navigation is a feature of some GPS navigation devices where directions for a selected route are continually presented to the user in the form of spoken and visual instructions. The system keeps the user up-to-date about the best route to the destination, and is often updated according to changing factors such as traffic and road conditions. Turn-by-turn systems typically use an electronic voice to inform the user whether to turn left or right, the street name, and how much distance to the turn.