The iodide ion is a negatively charged ion formed when iodine gains an electron. It is represented by the chemical symbol I⁻. Iodide is commonly found in nature, particularly in seawater and certain minerals, and plays a crucial role in biological processes, especially in the production of thyroid hormones. Iodide is essential for human health, as it helps regulate metabolism and supports proper growth and development. A deficiency in iodide can lead to health issues such as goiter and thyroid dysfunction. Iodide is also used in various applications, including medical imaging and as a dietary supplement.