Priority to the right is a right-of-way system, in which the driver of a vehicle is required to give way to vehicles approaching from the right at junctions.
The priority to the right rule applies when two roads (where neither is a priority road) cross each other and nothing else regulates the duty to give way at the junction.
The priority to the right rule also applies when two vehicles' paths cross each other in open areas, such as in parking lots and petrol stations.