Fair Isle is a traditional knitting technique used to create patterns with multiple colours. It is named after Fair Isle, a tiny island in the north of Scotland, that forms part of the Shetland islands. Fair Isle knitting gained a considerable popularity when the Prince of Wales (later to become Edward VIII) wore Fair Isle tank tops in public in 1921. Traditional Fair Isle patterns have a limited palette of five or so colours, use only two colours per row, are worked in the round, and limit the length of a run of any particular colour.
Some people use the term "Fair Isle" to refer to any colourwork knitting where stitches are knit alternately in various colours, with the unused colours stranded across the back of the work. Others use the term "stranded colourwork" for the generic technique, and reserve the term "Fair Isle" for the characteristic patterns of the Shetland Islands.