The common name for the safety device that inflates rapidly during a collision is an airbag. It is a vehicle occupant-restraint system designed to cushion people and reduce contact with the steering wheel, dashboard, doors, pillars or windshield.
Crash sensors monitor a collision and send information to an electronic control unit. If the impact meets the system’s deployment threshold, an inflator rapidly fills a folded fabric bag with gas. The bag then vents in a controlled way as the occupant moves into it, helping spread deceleration over more time and body area.
An airbag is supplemental protection, not a replacement for a seatbelt. Seatbelts restrain occupants and position them correctly for the airbag to work effectively. A bumper absorbs or redirects some crash energy, while a crumple zone helps deform the vehicle structure; neither inflates around occupants. Modern vehicles can include frontal, side, curtain, knee and other specialized airbags.