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Unit prefix
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<p>A unit prefix is a specifier or mnemonic that is added to the beginning of a <a href="/facts/Unit_of_measurement/pvTpWbmC">unit of measurement</a> to indicate multiples or fractions of the units. Units of various <a href="/facts/Order_of_magnitude/cWzRP2dM">sizes</a> are commonly formed by the use of such <a href="/facts/Prefix/C4Lw8npg">prefixes</a>. The <a href="/facts/Metric_prefix/Y2MzkaeL">prefixes of the metric system</a>, such as <i><a href="/facts/Kilo-/akxTdXyp">kilo</a></i> and <i><a href="/facts/Milli-/h1TVNfuW">milli</a></i>, represent multiplication by positive or negative <a href="/facts/Exponentiation/pac6QY2g">powers</a> of ten. In information technology it is common to use <a href="/facts/Binary_prefixes/oM3wgJgW">binary prefixes</a>, which are based on <a href="/facts/Power_of_2/MA6WEpTt">powers of two</a>. Historically, many prefixes have been used or proposed by various sources, but only a narrow set has been recognised by standards organisations. </p>