It is easier to compare different rates and, provided that the unit rate is simple, the equation for conversion is also simple.
It is a unit rate.
The unit rate.
It is a unit rate.
It is called a unit rate.
It is called a unit rate.
It is called a unit rate.
It is called a unit rate.
It is called a unit rate.
If the numerator is 1, it's a unit rate.
A unit rate always has a 1 as a denominator.
It becomes a unit ratio.
You rename the rate such that either the numerator, or the denominator is 1. It is usually the denominator, but can be the numerator.