Joseph and Jacques Etienne Montgolfier were French brothers. The two brothers had to leave school early in order to help their father at a paper factory. In 1782, while working at the paper factory they discovered that putting hot air in a bag caused it to rise. The brothers invented the first successful hot air balloon in 1783. A hot air balloon is a large balloon contains hot air. The hot air causes the balloon to rise. A hot-air balloon usually has a basket on the bottom. The basket can hold people and other things. Hot-air balloons are used for transportation and have been used during wartime.