Metric prefixes are symbols added to the base unit of measurement in the metric system to indicate multiples or fractions of that unit. For example, the prefix "kilo-" means one thousand, so one kilometer is 1,000 meters. Other common prefixes include "centi-" for one-hundredth and "milli-" for one-thousandth. These prefixes help simplify communication about measurements by providing a clear way to express large or small quantities. For instance, instead of saying 0.001 grams, one can say 1 milligram. This system is widely used in science, engineering, and everyday life, making it easier to understand and compare different measurements.