Arrhenius bases are substances that increase the concentration of hydroxide ions (OH⁻) in an aqueous solution. According to Svante Arrhenius, who proposed this theory in the late 19th century, a base is defined by its ability to dissociate in water, releasing hydroxide ions. Common examples of Arrhenius bases include sodium hydroxide (NaOH) and potassium hydroxide (KOH). When an Arrhenius base dissolves in water, it reacts with water molecules, leading to a rise in pH and making the solution more alkaline. This property is essential in various applications, including neutralizing acids and in many industrial processes.