In economics, the difference between the total amount consumers would be willing to pay to consume the quantity of goods transacted on the market and the amount they actually have to pay for those goods. The former is generally interpreted as the monetary value of consumer satisfaction. The concept was developed in 1844 by the French civil engineer Arsène-Jules-Étienne-Juvénal Dupuit (1804-1866) and popularized by Alfred Marshall. Though economists adopted a nonquantifiable approach to consumer satisfaction in the 20th century, the concept is used extensively in the fields of welfare economics and taxation