The hydroxide ion, represented as OH-, is a negatively charged ion composed of one oxygen atom and one hydrogen atom. It plays a crucial role in chemistry, particularly in acid-base reactions. When dissolved in water, hydroxide ions can increase the pH of a solution, making it more basic or alkaline. Hydroxide ions are commonly found in various substances, such as sodium hydroxide (lye) and potassium hydroxide. They are essential in many industrial processes, including the production of soaps and detergents. Additionally, hydroxide ions are important in biological systems, where they help maintain pH balance in cells.