what is µ
Micro- (symbol Î¼) is a unit prefix in the metric system denoting a factor of 10â6 (one millionth). Confirmed in 1960, the prefix comes from the Greek Î¼Î¹ÎºÏÏÏ (mikrÃ³s), meaning small. The symbol for the prefix comes from the Greek letter Î¼ (mu).