Asker (Norwegian: Asker), properly called Askerbygda in Norwegian, is a district and former municipality in Akershus, Norway. From 2020 it is part of the larger administrative municipality Asker, Viken (also known as Greater Asker) in Viken county, together with the traditional Buskerud districts Røyken and Hurum; Asker proper constitutes the northern fourth and is part of the Greater Oslo Region. The administrative centre was the town of Asker, which remains so for the new larger municipality. Asker was established as a parish in the Middle Ages and as a municipality on 1 January 1838.