Bicarbonate is a polyatomic ion whose formula is HCO3-. It is the intermediate form in the deprotonation of carbonic acid: removing the first proton from carbonic acid forms bicarbonate; removing the second proton leads to the carbonate ion.
The salts which contain the bicarbonate ion are also known as bicarbonates, such as sodium bicarbonate (baking soda) NaHCO3. Bicarbonates, when exposed to an acid such as acetic acid of vinegar, release carbon dioxide. This is used to cause breads to rise in cooking and to propel toy rockets.
Bicarbonates are more correctly named hydrogencarbonates in the chemical nomenclature system.