Image courtesy off-road.com

Spotters are people that help riders or drivers see more than they normally would by themselves. They're used in several settings of off-roading, including rock crawling and jumping. Spotters when jumping are very important when you jump in public areas and other people may be in the area you will be jumping.

Any time you're jumping over ridges in areas where others may cross your path that you cannot see or they cannot see you, you need to use a spotter. You usually can't see over what ever you're jumping, or if there are other people headed towards the area you will be jumping. Having a spotter gives you and those riding around you much better chances of avoiding a collision.

Your spotter usually stands at the top of the jump, where they are the most visible to you and others, and have a clear view of the landing path. The spotter's biggest responsibility is NOT to keep others out of your landing path, but to inform you when there's nobody in your path, or headed for your path and that it's OK to jump.