Answer:

Imperial units are the traditional units of measurement. In many countries they have now been replaced by metric units. In imperial units length is measured in inches, feet, yards, miles; mass is measured in ounces, pounds, stones, hundredweights, tons; capacity is measured in pints, quarts, gallons.

The units were introduced in the United Kingdom and its colonies, including Commonwealth countries (most have since become officially metric, but continue to use both Metric and Imperial), but excluding United States. Systems of imperial units are sometimes referred to as foot-pound-second, after the base units of length, mass and time.