The normal location of the thyroid gland is above the sternum, in front of the neck, on both sides of the upper trachea, and below the thyroid cartilage, 2-3 cm below the laryngeal node, with two lobes, the left and the right, and a narrower part between them in front of the trachea, called the isthmus of the thyroid. The thyroid gland is shaped like a butterfly. It is covered by the pre-tracheal fascia and is fixed to the tracheal ring, so that it moves up and down with the trachea during swallowing movements. There are also individual thyroid glands that are located lower down, even partially behind the sternum, called the retrosternal thyroid. Clinically, when touching the thyroid gland or touching a thyroid swelling, the patient is asked to do a swallowing motion to feel if the thyroid gland is enlarged and if the thyroid swelling moves up and down with swallowing. The thyroid gland is the largest endocrine gland in the body, and thyroxine, which is synthesized and secreted by the thyroid gland, is one of the most important hormones in the body, controlling the metabolic activities of the body and is an essential hormone for human health. Hyperthyroidism and hypothyroidism can have a significant impact on human health.