<Table> <Tr> <Td> </Td> <Td> This article includes a list of references, but its sources remain unclear because it has insufficient inline citations . Please help to improve this article by introducing more precise citations . (December 2017) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article includes a list of references, but its sources remain unclear because it has insufficient inline citations . Please help to improve this article by introducing more precise citations . (December 2017) (Learn how and when to remove this template message) </Td> </Tr> <P> In economics, demand is the quantities of a commodity or a service that people are willing AND able to buy at various prices, over a given period of time . </P> <P> The relationship between price and quantity demanded is also known as demand curve . Preferences and choices, which underlie demand, can be represented as functions of cost, benefit, odds and other variables . </P>

When is an item considered to be in demand