The thyroid and parathyroid glands are integral components of the endocrine system, critically involved in metabolic regulation, calcium homeostasis, and overall physiological equilibrium. Thyroid and parathyroid glands have an intricated developmental origin and anatomical relationships that underpin safe surgical practice. Historically, thyroid surgery has evolved substantially from the era before the early nineteenth century, when it was fraught with complications and mortality as much as 40%. Advances in embryological and anatomical understanding, surgical techniques, anesthesia, and postoperative care have dramatically improved patient outcomes. The pioneering works of Theodor Kocher and William Halsted laid the foundational principles of meticulous surgical technique, accurate anatomical dissection, and careful hemostasis, transforming thyroid surgery into a procedure with very low morbidity and mortality rates. The modern thyroid surgeon must have a thorough understanding of the developmental origin, detailed anatomy, and applied anatomy of the thyroid and parathyroid glands to execute safe and standard surgery, while avoiding complications such as nerve injury or hypoparathyroidism during neck surgery. This chapter reviews the embryology of the thyroid and parathyroid glands, details their surgical anatomy (including important classifications of laryngeal nerves and embryologic remnants), and highlights key surgical landmarks (e.g., triangles and planes) that guide surgeons in performing safe and effective thyroid surgery.