The incidence of thyroid cancer is increasing rapidly. A large percentage of new cases identified fall into a low-risk category. As the incidence has increased, clinical experience has confirmed that the majority of patients will have excellent outcomes and that those at risk of doing badly can be reliably identified. Treatment for thyroid cancer is predominantly surgical. The decision about how aggressively this disease should be managed has remained controversial due to the excellent outcomes irrespective of the nature of surgical procedure chosen. This article reviews the developments in our understanding of the biology of thyroid cancer and the evidence that supports the approach to management.