Carbonic acid is the organic compound with the formula H2CO3 (equivalently OC(OH)2). It is also a name sometimes given to solutions of carbon dioxide in water (carbonated water), because such solutions contain small amounts of H2CO3. Carbonic acid, which is a weak acid, forms two kinds of salts, the carbonates and the bicarbonates.
Read more about Carbonic Acid: Chemical Equilibrium, Role of Carbonic Acid in Blood, Role of Carbonic Acid in Ocean Chemistry, Acidity of Carbonic Acid, Spectroscopic Studies of Carbonic Acid