Seat belts are designed to retain people in their seats during a crash, and so prevent or reduce injuries. They minimise contact between the occupant and vehicle interior and significantly reduce the risk of being ejected from the vehicle.
On modern vehicles, seat belts are also designed to work as the key part of wider injury prevention measures and safety systems, such as airbags and head restraints, which will not be as effective in reducing the risk of injury if an occupant is not wearing a seat belt.
Car occupants form 64% of all road casualties in Britain. In 2011, 124,924 people were killed or injured while travelling in cars, of these 89,787 (67%) were drivers.