Q.Define demand. Distinguish between desire and demand with a suitable example.

Demand is desire backed by both willingness and ability to pay, unlike a bare wish.

Demand, in economics, is the quantity of a good or service that a consumer is both willing and able to purchase at a given price, during a given time period, other things remaining the same.

Desire vs demand: A desire is simply a wish to own or consume something, with no requirement that the person can or will pay for it. It becomes economic demand only when TWO further conditions are met: (i) the consumer is WILLING to spend money to satisfy the wish, and (ii) the consumer has the ABILITY (purchasing power) to actually pay for it.

Example: A daily-wage labourer may strongly wish to own a two-wheeler — that is a desire. The moment she saves enough money and is prepared to spend it on the two-wheeler at the market price, her wish becomes demand. If she still cannot afford it despite wishing for it, it remains a desire only, never demand, however strongly she wants it.

This is precisely why national income and market-size statistics count only backed, payable demand — an unmet desire, however widespread, does not show up in a market's demand schedule at all.

Defining demand as simply "wanting something" without mentioning price, time period, and the willingness-plus-ability condition loses most of the marks on this standard definitional question.