An Arrhenius acid is a substance that increases the concentration of hydrogen ions (H⁺) in an aqueous solution. This definition was proposed by the Swedish chemist Svante Arrhenius in the late 19th century. When an Arrhenius acid dissolves in water, it dissociates to release H⁺ ions, which can react with other substances. Common examples of Arrhenius acids include hydrochloric acid (HCl) and sulfuric acid (H₂SO₄). These acids are often used in various applications, such as cleaning agents and chemical reactions. Understanding Arrhenius acids is fundamental in the study of acid-base chemistry.