Hydrogen is a chemical element; it has the symbol H and atomic number 1. It is the lightest and most abundant chemical element in the universe, constituting about 75% of all normal matter.
The earliest known chemical property of hydrogen is that it burns with oxygen to form water; indeed, the name hydrogen is derived from Greek words meaning ‘maker of water.’
Hydrogen is a clean alternative to methane, also known as natural gas. It's the most abundant chemical element, estimated to contribute 75% of the mass of the universe. Here on earth, vast numbers of hydrogen atoms are contained in water, plants, animals and, of course, humans.