The International Metric System is used to define units like centimeter, meter, kilometer grams, kilograms, milliliters, liters, and other units. It is in use in numerous Latin American countries. Conversions refer to the conversion of one unit to the next, and can occur when they are of similar measurements. As an example, conversions can be done between units of distance which is, in this instance, centimeters and kilometers. Conversions can’t be made the distinction between kilograms and kilometers because they’re different measurement or magnitudes.