The Brønsted-Lowry theory defines acids and bases based on their ability to donate or accept protons (H⁺ ions). According to this theory, an acid is a substance that donates a proton, while a base is one that accepts a proton. This framework helps explain acid-base reactions in a broader range of chemical contexts. In a Brønsted-Lowry reaction, the transfer of protons occurs between the acid and the base, resulting in the formation of a conjugate base from the acid and a conjugate acid from the base. This concept is essential for understanding various chemical processes, including neutralization and buffer systems.