Formation lap
The formation lap is the single lap before the start, driven to bring tyres and brakes up to temperature before the cars return to the grid.
Also called parade lap
Drivers weave and brake hard deliberately — a Formula 1 tyre is close to useless cold, and the launch off the line depends on it being in its working range.
Overtaking is not allowed, and a driver who cannot get away must indicate it, which triggers an extra formation lap and shortens the race by one. A car that stops on it starts from the pit lane.