Alkali refers to a group of basic, water-soluble compounds that can neutralize acids. These substances typically contain the hydroxide ion OH⁻ and are derived from the alkali metals, such as sodium and potassium. When dissolved in water, alkalis produce a slippery feel and can change the color of indicators, like turning litmus paper blue. Common examples of alkalis include sodium hydroxide (lye) and potassium hydroxide. They are widely used in various industries, including cleaning products, food processing, and manufacturing. Alkalis play a crucial role in chemical reactions, particularly in neutralizing acids to maintain pH balance.