A co-driver is the navigator of a rally car in the sport of rallying, who sits in the front passenger seat. The co-driver's job is to navigate, by reading off a set of pacenotes to the driver, often over a radio headset, due to the high level of noise in the car. The co-driver tells the driver what lies ahead, where to turn, the severity of the turn, and what obstacles to look out for, and any incidents or accidents that may have occurred further ahead in the stage. This role is particularly critical in high-end rally competitions such as WRC. Co-drivers are also often called on to perform maintenance on the car during road sections and special stages, such as changing a wheel.