What is a Mill and how is it used?

A mill is one-thousandth of one dollar. Just as you would write
$1.00 for one dollar; and $.10 for a dime, or one-tenth of a dollar;
or $.01 for a penny, or one-hundredth of a dollar; you would write
.001, or one-thousandth of a dollar, for one (1) mill. When you hear
the expression 54.5 mills, that is the same thing as the factor .0545.

Property Types (Classes of Property for Taxes)

Mississippi law lists five categories of property that are taxed for ad
valorem purposes. Real property (land, buildings, and other permanent improvements to the land) is divided into the first two classes
of taxable property.