Foot (unit of length)
A foot is a unit of length, the original measure being the length of a man's foot.
The most commonly used foot today is the imperial unit, the foot currently defined to be 0.3048 meters. This unit is sometimes denoted with an apostrophe (ex. 30' = 30 feet).
The foot as a measure was used in almost all cultures. The first known standard foot measure was from Sumeria, where a definition is given in a statue of Gudea of Lagash from around 2575 BC. The imperial foot was adapted from an Egyptian measure by the Greeks, with a subsequent larger foot being adopted by the Romans.
In addition to the current standard imperial foot, there is also a slightly different U.S. survey foot, used only by the U.S. Coast and Geodetic Survey, defined as exactly 12 U.S. survey inches, approximately 30.48006 cm. (See inch for more on the survey inch.)
