The thyroid is a butterfly-shaped gland located in front of the neck, on both sides of the trachea just above the collarbone. It is one of the endocrine glands responsible for production of important hormones that help to regulate the body's metabolism and affects vital processes of the body, such as growth, the development of the fetus in the womb, thermoregulation and ensuring the normal operation of the cardiovascular system. The thyroid gland accumulates iodine, ingested with food and uses it in the production of the special hormones. The main problems associated with the gland usually arise when it becomes overactive (hyperthyroidism) or under-active (hypothyroidism), various anatomical problems, deficiencies and tumors. Learn more about the functions and structure of the thyroid, its hormones, as well as diseases associated with the gland and their treatments in this book.