Final answer:
The metric prefix "micro" represents a factor of 10^-6, meaning one-millionth of the base unit.
Step-by-step explanation:
The unit prefix "micro" in the metric system denotes a factor of 10^-6 (one millionth). In the metric system, units are categorized by their size in factors of ten to make measurements easier and more precise. For example, using the prefix 'centi,' which represents 10^-2, we write 'cm' to denote 1/100 of a meter. Similarly, 'mm' means millimeter, where 'm' represents a milli- or 10^-3, which is 1/1000 of a meter. The prefix 'micro' is thus used to describe even smaller measurements, signifying 1/1,000,000 of the base unit.