The modern three-point automotive seat belt was the brainchild of Swedish aircraft engineer Nils Ivar Bohlin, who, ironically, spent the early years of his career designing aircraft ejector seats. Nevertheless, Bohlin's invention - a three-point combination lap and diagonal belt positioned across the pelvis and rib cage - has saved thousands of lives since its introduction in 1959.

Seat belts today, of course, are an accepted part of routine vehicle operation for millions of drivers and passengers. Unfortunately, millions of other vehicle occupants continue to put their lives at risk by ignoring these critical restraint systems.

Seat belts are a marvel of complexity and simplicity. They combine Bohlin's strong three-point harness with a relatively simple pendulum and ratchet mechanism that locks the belt in sudden-stop situations. This design helps improve the comfort of belt wearers, as the belt is not locked in position under normal operation.

As with any safety system, however, seat belt performance is dependent on proper use and fit. If the belt is not positioned correctly on the vehicle occupant's body, it can fail to provide adequate safety in the event of a collision or rapid deceleration.

Here are some tips to ensure that your belts provide the safety you and your passengers deserve: Always wear your seat belt, and insist that your passengers do the same. One non-restrained passenger can seriously injure others in the vehicle. Seat belts help prevent internal injuries by spreading the force of a collision across two of the human body's strongest areas - the pelvis and upper chest. To ensure the proper distribution of force, the lap belt should be positioned across the upper thighs, and the diagonal belt across the chest. Never slip the diagonal belt behind your body; the lap belt alone cannot prevent you from being thrown forward and out of the vehicle. The lap belt also must be used at all times. Without this restraint, your body would simply be thrown under the diagonal belt and into the dashboard or steering wheel. Make sure your belt fits snugly against your body; if it is too loose, you could be injured by being thrown against the belt itself. If your seat belts don't seem to operate correctly, or you cannot adequately adjust them, return the car to a dealership or qualified repair shop for assistance. If your vehicle is fitted only with lap belts (pre-1974 models), contact a dealership for an upgrade to a three-point harness. Aftermarket kits are available for many vehicle makes and models.

Facts: Three of five people killed in vehicle accidents would have survived their injuries had they been wearing their seat belts. (Source: National Highway Traffic Safety Administration) Seat belts save an estimated 9,500 lives in the United States each year. (Source: NHTSA) Every 13 minutes, someone is killed in a traffic accident. (Source: NHTSA)