An airbag is a safety device in vehicles designed to protect passengers during a crash. It is made of a flexible fabric that inflates rapidly when a collision occurs, creating a cushion that absorbs the impact. This helps to reduce the risk of serious injuries to the head and chest, making it an essential feature in modern cars. When a car's sensors detect a sudden stop or impact, they trigger the airbag to deploy in milliseconds. This quick response is crucial for safety, and airbags are often used in conjunction with seatbelts to provide maximum protection. Together, they help save lives on the road.