In the pits on qualifying and practice days, you can see the inner workings of the teams and the cars. The Lotus looks fast even up on its stands. Facing the opposite direction, watching the cars drive away from the corner, is the yellow flagger. If a car passes the turn and then spins or crashes, this corner worker quickly spins around and starts waving the yellow flag to warn approaching racers of the danger. This alerts the drivers to an abnormal situation without restricting their racing.
Some organizations use the black flag to order drivers to slow down and proceed to the pits.
Other workers in each corner station are responsible for fire extinguishers, or are on standby to help push a stricken car out of the racing line. They also help spot incidents, communicate with the other corners visually and control overzealous photographers and race fans, when necessary. The workers take turns in most roles. Fatigue especially affects the people working communications and blue-flagging, because of the concentration required. Without these folks at each corner, not a single car would be on the track.