A balloon is a bag filled with heated air or a light gas so that it rises and floats in the air. A balloon rises because the heated air or gas inside is less dense than the surrounding air. Hot-air balloons are mainly use for sporting and they rise because the air inside the balloon is warmer and lighter than the surrounding air. Charles' Law explains how this is possible. It states that the volume of a gas increases as its temperature increases and if its pressure stays the same.
Gas balloons are use for sport ballooning, scientific research, and many other purposes.
These balloons may be filled with hydrogen, helium, or natural gas. The four most important kinds of gas balloons are the sport balloons, expandable balloons, super pressure balloons, and the zero-pressure balloon. The last three are used for scientific purposes. Ever since the first hot-air balloon in France in 1783, many improvements have been made. Balloons started to reach higher altitudes.