An air bag is an inflatable rubber-lined nylon bag or cushion designed in such a way to protect automobile occupants from serious injury in case a collision occurs. It is also known as an air cushion restraint system (ACRS) or an air bag supplemental restraint system (SRS). While seat belts are always there, especially in side impacts, rear impacts, and rollovers, to hold the occupant securely in place, the air bag is designed as an add-on protection offered by seat belts. Upon detecting a collision, air bags inflate instantly thereby providing the exposed occupant with a big gas-filled pillow or cushion.

For many years, air bags have been under development. The first patent on an inflatable crash-landing device for airplanes was filed during World War II. The first commercial air bags appeared in automobiles in the 1980s.

For industrial purpose, an air bag is a large inflatable bag made of strong rubber which is used by rescue workers to lift a trapped victim or a vehicle or heavy machinery or debris that has fallen upon. It is particularly effective in preventing life-threatening and debilitating head and chest injuries. The trucking and transportation industries are usually provided with custom-made rubber air bags. A molded rubber air bag is used for truck air ride systems. This product is specially designed to be used on trucks that transport delicate and sensitive equipment that require a maximum reduction in the shock and vibration on the road.

The air bag is sewn from a woven nylon fabric or any synthetic rubber like silicone or EPDM and can come in different shapes and sizes depending on specific vehicle requirements. The rubber material air bag is also provided with a heat shield coating to protect the fabric from scorching, especially near the inflator assembly, during deployment. In some cases, talcum powder or corn starch is also used to coat the air bag which prevents the fabric from sticking together and makes it easier to assemble. Nowadays, newer silicone and urethane coated rubber air bag materials require little or no heat shield coating.

The future for rubber air bags looks extremely promising because there are many different applications possible, ranging from aircraft seating to cars to motorcycle helmets.