Shetland Islands, archipelago, northern Scotland, in the North Atlantic Ocean, constituting Shetland Island Area (an administrative region), northeast of the Orkney Islands. The archipelago consists of about 100 rugged islands and islets, of which only 19 are inhabited. Mainland is the largest of the group. Other important islands are Yell, Unst, Fetlar, Whalsay, Bressay, Muckle Roe, and Fair Isle. Lerwick, on Mainland, is the administrative center and the largest town. The chief industry is fishing, and the islanders also raise cattle and sheep and cultivate crops for their own use. Principal exports are the famous Shetland ponies and the wool, knitwear, and hosiery that is manufactured by the women. In the 8th and 9th centuries the Shetland Islands were invaded by the Vikings, who ruled them until 1472, when they were added to the domains of the kings of Scotland. In November 1939 the islands were the target of the first German air raids on Britain in World War II. Lack of industry and high unemployment caused the islands' population to decline after 1871. Before 1975 the Shetland Islands constituted Zetland County, Scotland. Area, 1,438 sq km (555 sq mi); population (2001) 21,988.