The purpose of pre-stage is to control the flow of all competition vehicles to the start line.
The benefit to competitors is that they are not queued for long periods of time, far away from the pits without their support crews, shade, water etc.
The pre-stage area is located in the southern end of the pits. When vehicles are ready to race they must join the end of the queue in the pre-stage area.
The Starter will radio Pre-Stage when to send a group of vehicles to the start line. Typically this will be in groups of ten.