Mile is a unit of length used in the imperial and US customary systems of measurement. It is defined as the distance covered by one thousandth of a degree of latitude or longitude, and is used to measure both straight line distance (as the crow flies) and distances on Earth's surface. In the imperial system, one mile is defined as 1760 yards or 5280 feet, while in the US customary system it is defined as 5280 feet.