A lap belt is a type of safety belt designed to secure a person in a vehicle. It goes across the lap, typically resting on the thighs, and helps keep the occupant in place during sudden stops or accidents. This belt is an essential part of vehicle safety systems, working alongside other restraints like shoulder belts to provide maximum protection. In many vehicles, especially older models, the lap belt is the only restraint available for passengers in the back seat. While it offers some level of safety, it is recommended to use a combination of both lap and shoulder belts for better protection, as they work together to reduce the risk of injury during a crash.