Thyroiditis is a common thyroid disorder that is more common in women. The clinical manifestations are varied, and the same type of thyroiditis can manifest at different times in the course of the disease not only as hyperthyroidism, but also as hypothyroidism, as diffuse thyroid lesions, and as thyroid nodules, and sometimes the different types of thyroiditis can be interchangeable. Therefore, thyroiditis involves all aspects of thyroid disease and requires differential diagnosis with many thyroid disorders, and it is important to understand the various types and clinical features of thyroiditis. The disease is classified according to the speed of onset into acute septic thyroiditis, subacute thyroiditis and chronic thyroiditis. 1. Subacute thyroiditis: It is divided into subacute granulomatous thyroiditis (i.e., subacute thyroiditis) and subacute lymphocytic thyroiditis (painless thyroiditis), which is further divided into sporadic thyroiditis and postpartum thyroiditis. 2. Chronic thyroiditis: This includes chronic lymphocytic thyroiditis (Hashimoto’s thyroiditis) and chronic fibrous thyroiditis.