A spotter in auto racing is a trained team member whose job is to relay information to their driver, keeping them alert of what is occurring on the track.
Spotters are considered the drivers' "eyes" and are one of the more notable yet simple, safety measures adopted by professional auto racing in the past two decades.
No tracks had video boards, and monitors carrying the satellite feeds of the race telecast (which is standard in the pit areas nowadays) was still decades away.
The position gave the teams a unique view of the track, and allowed the "spotter" to relay information that could not be observed from the pits.
Also, before the teams possessed weather radar in the pits, the spotters could relay information about approaching rain, for strategic purposes.
For instance, spotters for two cars running together might consummate a deal for their respective drivers to pit together, that way they could re-enter the track together, as drafting partners.