A Brønsted-Lowry base is a substance that accepts a proton (H⁺ ion) in a chemical reaction.
An acid is a substance that donates or gives away a proton (H⁺ ion) in a chemical reaction.
In the context of acids and bases, the conjugate acid is formed when a base accepts or gains an additional proton.
Proton Donor: A proton donor refers to an acid, which donates or gives away its extra proton (H⁺ ion).