What is hydrogen?

Hydrogen accounts for about 90 percent of all atoms in the universe

Hydrogen is the simplest and most abundant element in the universe. It is essential for life and present in almost all living things. In its pure state, hydrogen is a gas of diatomic molecules with the formula H2. It is colourless, odourless, tasteless, non-toxic, highly flammable, and reactive. On earth, pure hydrogen is therefore very scarce – it mainly exists in the combination with oxygen in the form of water.