An airbag is a soft bag. 

An airbag is a soft bag in a car. 
Sensors feel the crash. They tell the car to blow up the bag. The bag is a soft cushion. 
It can work with your seat belt. The bag is a helper for the belt. This helps keep everyone safe on the road.
An airbag is a safety tool in a car. 
How does it work? First, crash sensors feel the hit. These sensors send news to a computer unit called an ECU. The ECU uses a special math rule called an algorithm. This rule decides if the bag needs to pop out. If it does, the bag inflates in just a few milliseconds. This happens very fast! Most bags use a small chemical reaction to fill up. Some newer side airbags use compressed air instead.
Airbags are called "passive" restraints. This means they work without you doing anything. This is different from seat belts. Seat belts are "active" because you must buckle them. Today, airbags work with seat belts to help keep you safe. 
An airbag is a special safety tool inside a vehicle. 
How does the airbag work during a crash? First, crash sensors feel the impact of the collision. These sensors send important data to a computer unit called an ECU. This unit uses a crash algorithm to decide if the bag should deploy. The algorithm looks at the type and the angle of the hit. If the crash meets certain rules, the ECU triggers a firing circuit. Most airbags use a pyrotechnic process to inflate. This means a small chemical reaction happens to fill the bag. This whole thing happens in just a few milliseconds. 
The history of the airbag is very long. In 1919, two dentists named Arthur Parrott and Harold Round filed a patent. Their idea was for covering parts of vehicles and airplanes. Later, an American named John W. Hetrick filed a patent in 1952. He was an industrial engineer in the United States Navy. He wanted to protect his family on the road. He used his experience with navy torpedoes to help design it. 
Many people helped make the airbag what it is today. In 1967, Allen K. Breed invented a sensor using a ball in a tube. This sensor could inflate an airbag in under 30 milliseconds. In the 1970s, General Motors began offering airbags in some cars. They called their system the Air Cushion Restraint System, or ACRS. These early cars included a 1974-style Oldsmobile instrument panel. 
It is helpful to know how airbags fit with other safety tools. Airbags are called "passive" restraints. This means they work without you doing anything at all. This is different from seat belts, which are "active" restraints. You must actively buckle a seat belt to use it. Because of this, airbags are meant to be a supplement to seat belts. They work together to keep people safe during a crash.
An airbag, also known as a supplemental inflatable restraint, is a critical vehicle safety system. 
The mechanism of deployment relies on a complex chain of electronic and chemical events. First, crash sensors in the vehicle detect an impact. These sensors send data regarding the collision type, angle, and severity to the airbag electronic controller unit (ECU). The ECU then runs a crash algorithm to determine if the impact meets specific deployment criteria. If the criteria are met, the ECU triggers firing circuits. Most traditional modules use a pyrotechnic process, which is a chemical reaction, to inflate the bag in milliseconds. Newer side-impact modules may instead use compressed-air cylinders to achieve inflation.
Modern vehicles utilize a wide variety of airbag configurations to protect different parts of the body. A single car may contain up to ten different airbag modules. These include driver and passenger frontal airbags, as well as side-curtain airbags. Other types include seat-mounted, door-mounted, and pillar-mounted modules for side impacts. There are also specialized designs like knee bolsters, inflatable seat belts, and even pedestrian airbag modules.
The history of the airbag spans over a century of engineering. The earliest origins trace back to a 1919 patent by two dentists, Arthur Parrott and Harold Round. In 1952, American industrial engineer John W. Hetrick filed a patent for an automobile airbag. Hetrick used his experience with United States Navy torpedoes to develop his design. 
Commercial adoption of airbags evolved through several distinct phases. In the early 1970s, General Motors offered the Air Cushion Restraint System (ACRS) in certain fleet vehicles. These early systems included a driver-side airbag and a passenger-side cushion that protected both the torso and knees. 
It is important to distinguish between different types of vehicle safety. Airbags are classified as "passive" restraints because they require no action from the occupant to work. In contrast, seat belts are "active" restraints because a person must manually buckle them.
Today, the airbag is a standard component of global automotive safety. The transition from seeing airbags as seat-belt replacements to seeing them as supplemental systems has improved occupant protection. For example, Mercedes-Benz introduced an integrated system in 1981 that tensioned seat belts and deployed airbags simultaneously. 
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