Goiter is a chronic condition in which the thyroid gland is hard and moves up and down with the body’s swallowing movements. The severity of goiter is determined by the type of disease and the histological type of the accompanying tumor, the size of the tumor, and the clinical features. The incidence of goiter is increasing year by year, usually due to exposure to ionizing radiation, changes in iodine intake, and prolonged overexposure to diagnostic radiological imaging. The most common type of goiter is iodine deficiency disease, which is caused by a lack of iodine in the diet or an increase in the body’s iodine requirements without timely supplementation. This type of goiter is mainly caused by the hyperplasia of the follicular tissue of the thyroid gland and is a benign disease. Active iodine supplementation can be effective in preventing and treating this type of goiter. Goiter may also be due to the growth of a thyroid mass. A large percentage of goiters due to these causes are benign. Benign masses are generally slow growing and do not have aggressive growth characteristics, so these types of masses are less harmful and are not a serious disease. However, masses of this nature may become relatively severe due to the specific growth site that can cause some symptoms of tracheal and nerve compression. Surgical removal of this type of mass is possible, and the treatment is all the more effective. Among the types of goiter formation, thyroid cancer is one of the more serious diseases. Most of the thyroid cancers are not very malignant, but a few undifferentiated and medullary cancers are more malignant. Because it is a cancerous disease, some typical features of cancerous tissues such as metastasis to distant organs may occur, which can be life-threatening and undifferentiated thyroid cancer has a relatively high death rate due to its high malignancy. Most of the goiters are not serious diseases. A few of them are malignant in nature but can have a great impact on human health.