A spotter is a person assigned to guide a forklift operator by sight and hand signals when the operator's view is blocked, such as with a tall load, a tight maneuver or reversing in a crowded area.
29 CFR 1910.178 does not use the word spotter. It requires the operator to look in the direction of travel and keep a clear view of the path, to slow down and sound the horn where vision is obstructed, and to travel with the load trailing when it blocks forward view. Where none of that is practical, a spotter is the administrative control many sites use.
A spotter works only with agreed hand signals, a position where the operator can see the spotter at all times, a rule that the operator stops when the spotter is out of sight, and training for the spotter on truck movement and blind spots. The spotter is also a pedestrian working close to a moving truck, so a struck-by risk remains. Cameras and rear detection can reduce how often a spotter is needed but do not replace one in every case. See the forklift spotter guide.