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. 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.