Imperial System of UNITS
In the imperial system the base quantities are length with units in inches,feet,yards and miles,time with units same as in SI in seconds (s),hours (hr), days (d),weeks and year.
Weight with units in pound (lb) and Temperature with units in Fahrenheit.
Imperial systems commonly uses weight,rather than mass. Weight refers to the gravitational force on an object,whereas mass refers to the amount of matter of an object. An object has same mass on the moon as it does the earth,but it weights less on the moon as the gravitational force of the moon is less than gravitational force of the earth.
Know about SI unit system What is SI unit?