Demand Function

The demand function shows the relation be­tween the quantity demanded of a commodity by the consumers and the price of the product. These functions are probably the most important tools used by economists. While many variables deter­mine the quantity consumers wish to purchase in a market, the price of the commodity is perhaps the most important one.

A demand function is a list of prices and the cor­responding quantities that individuals are willing and able to buy at a fixed point of time. We may note at the outset that demand is a function (or schedule), not a specific quantity. It is formally de­fined as a schedule of the total quantities of a com­modity or service that will be purchased at various prices at a particular point of time.

Hence when we refer to the demand for meat or the demand for mo­tors cars in India, we are considering the amounts that consumers are willing and able to purchases at various prices.
The word ‘demand’ is a broad con­cept referring to the entire schedule of quantities and prices. But the term ‘quantity demanded’ refers to a single point on the demand schedule or curve. It shows the maximum quantity demanded at a par­ticular price.

We can express demand as a func­tion
                                                               Qx = ƒ(Px)

In this function, the other variables (income, and so on) are held constant. The quantity demanded of a commodity is a function of the price of the good, holding constant the other (proximate) determi­nants of demand.