Thyroid nodules are common clinically and even more common as an incidental finding during ultrasonography. Routine screening of thyroid nodules in patients with hyperthyroidism or hypothyroidism without risk factors for thyroid cancer is not recommended. Most thyroid nodules are benign. Sonographic risk-stratification systems should be used to estimate the risk of malignancy and the need for fine-needle aspiration biopsy. Malignant thyroid nodules require surgical management. Most thyroid cancers are well-differentiated papillary or follicular thyroid neoplasms, which have an excellent prognosis with a low mortality rate.