Polyprotic acids, also known as polybasic acids, are able to donate more than one proton per acid molecule, in contrast to monoprotic acids that only donate one proton per molecule. Specific types of polyprotic acids have more specific names, such as diprotic (or dibasic) acid (two potential protons to donate), and triprotic (or tribasic) acid (three potential protons to donate). Some macromolecules such as proteins and nucleic acids can have a very large number of acidic protons. https://en.wikipedia.org/wiki/Acid#Polyprotic_acids
In chemistry, carbonic acid is a dibasic acid with the chemical formula H2CO3. The pure compound decomposes at temperatures greater than about ?80 °C.
In biochemistry and physiology, the name "carbonic acid" is often applied to aqueous solutions of carbon dioxide, which play an important role in the bicarbonate buffer system, used to maintain acid–base homeostasis. https://en.wikipedia.org/wiki/Carbonic_acid