Chloride (Cl⁻) is a negatively charged ion, known as an anion, formed when chlorine gains an electron. It is commonly found in nature, especially in seawater, where it exists as part of sodium chloride, or table salt. Chloride plays a crucial role in maintaining fluid balance in the body and is essential for various biological processes. In addition to its biological importance, chloride is used in many industrial applications. It is involved in the production of chemicals, such as hydrochloric acid, and is also used in water treatment to help disinfect and purify drinking water.