Levy imposed on the sale of goods and services. A sales tax on the manufacture, purchase, sale, or consumption of a specific commodity is known as an excise tax. Though excise taxes have been used since ancient times, the general sales tax is a comparatively recent innovation. Sales taxes are ad valorem taxes, imposed according to the value (i.e., monetary value) of the taxable commodity. They are classified according to the levels of business activity at which they are imposedproduction, wholesale, or retail. They account for significant portions of the revenue of most U.S. states and Canadian provinces. A variation of the sales tax, the value-added tax, became popular in western European countries and is widely used. Most sales taxes are borne by the consumer, since even where they are levied on production or wholesale goods, part or all of the cost is shifted to the consumer in the form of higher prices. Because the retail sales tax is considered a regressive tax, essential goods such as food, clothing, or drugs are sometimes exempted or taxed at a lower level. See alsoincome tax; progressive tax.