Steam is fundamentally composed of water molecules. The chemical formula for water is H2O, which means each molecule consists of two hydrogen atoms and one oxygen atom. When water is heated to its boiling point, it transitions from a liquid state to a gaseous state, becoming steam.
In its gaseous form, steam can be considered as a collection of water vapor molecules. Despite its gaseous state, the chemical composition remains unchanged; it is still H2O. However, steam carries significant energy due to the heat that is added to the water, giving it properties that make it useful for various applications, particularly in heating and power generation.