Tax records are the result of taxation whereby civil authorities tax persons (usually heads of households) or property to acquire revenue for public purposes. The authorities determing the wealth (real estate, or income) that is to be taxed. There are different kinds of taxes: poll, personal, real estate, school and more.
You may learn more from the following article United States Taxation
Searching Tax Records
The records are usually arrange chronologically
Tax records contain the name of the individual subject to the tax, the item or items taxed and the amount taxed, sometimes heirs may be mentioned.
Tax records may be used when census records are unavailable. By studing several consecutive years of tax records you may determine when a young men came of age, when individulas move in and out, or die leaving heirs.
There are county tax rolls, some dating as early as the 1820s. The county treasurer may have these records, or they may have been transferred to the area research center for the region (see the list of area research centers in Archives and Libraries).