A megafire is an extraordinary fire that devastates a large area. They are characterized by their intensity, consequence, duration and uncontrollable dimension. There is no precise scientific definition, and the concept may vary by region or country. While in Europe they are characterized beginning at 1,000 hectares, in the United Statesthey may be noted beginning at 10,000 hectares. Another definition used in the United States is 100,000 acres.