Spotting is frequently used in bouldering. Spotters are often seen standing close to or underneath a boulderer. The job of a spotter is to ensure that if the climber falls, they will be directed, mid fall, to a safe landing area (usually a bouldering mat).
One common misconception is that the spotter is trying to catch the climber, however this is not the case and their role is to ensure the climber lands feet first safely. Verbal encouragement, pointers and general banter usually come with spotters.