The term conversion of units refers to changing an amount of a measurement unit into another unit. There are many different systems of units, so some conversions can be very complex. Most conversions involve a "conversion factor" (named "m"), and a shift amount (such as "b"), to change from a unit "x" into a unit "y" by the general equation: y = mx + b. That type of conversion is known as a "linear transform" or a mathematical "translation".