Spotter: A person whose primary responsibility is to prevent injuries by protecting the head, neck, back and shoulders area of a top person during the performance of a stunt, pyramid or toss. All “Spotters” must be your own team’s members and be trained in proper spotting techniques. The spotter:

If the spotter’s hand is under the top person’s foot it must be their front hand. Their (the spotter’s) back hand may be placed at the back of the ankle/leg of the top person or on the back side of the back wrist of the base.

(The definition used in the video is different, but the example shown in the video remains useful.)