Imperial unit and U.S. customary unit of area
The square foot (pl. square feet; abbreviated sq ft, sf, or ft 2 ; also denoted by 2 and ⏍) is an imperial unit and U.S. customary unit (non-SI, non-metric) of area, used mainly in the United States and partially in Canada, the United Kingdom, Bangladesh, India, Nepal, Pakistan, Ghana, Liberia, Malaysia, Myanmar, Singapore and Hong Kong. It is defined as the area of a square with sides of 1 foot. Wikipedia