Iodide anions are negatively charged ions formed when iodine gains an electron. They are represented by the chemical symbol I⁻ and are commonly found in nature, particularly in seawater and certain minerals. Iodide plays a crucial role in human health, as it is essential for the production of thyroid hormones, which regulate metabolism. In addition to their biological importance, iodide anions are used in various applications, including photography and medicine. For instance, potassium iodide is often used as a dietary supplement to prevent iodine deficiency and can also be used in radiation emergencies to protect the thyroid gland from harmful exposure.