Hydrogen forms part of water, and is the most common element (with carbon) in living things and fossil fuels. Nuclear fusion of hydrogen into helium causes the Sun to shine. This process is the opposite of that is used in the nuclear bomb.
In the 1930s, many airships, like the Hindenburg, were filled with hydrogen. Being so light, hydrogen would seem to be ideal for filling ballons and airships. However, because it is so explosive when combined with oxygen, it explodes easily. While the May 6, 1937 Hindenburg explosion probably wasn't started by the hydrogen, it may have made the disaster worse.
Experimental cars running on hydrogen have already been made. The advantage is that they do not pollute. However, they are less cost effective so it is hard to get people to buy them.
English scientist Henry Cavendish (1731-1810) found a gas he called "inflammable air." When he experimented with the gas, he discovered water was formed when the gas was burned with air. This discovery proved that water was not a seperate element, as previously thought. The gas was later called hydrogen.
--Wolfgang F, with help from Benjamin P