Demand in economics is schedule or curve that show the quantity of product purchased on series of prices during a specific time period period. The demand of any commodities creates when consumer have willingness and ability to buy the product on offered price.
Below table-1 show the hypothetical demand schedule for a single consumer purchasing number of apples.
An individual Buyer’s demand for Apple
The market didn’t accept the willingness of consumer but also the ability purchase is mandatory. Suppose, if you are willing to buy a camera but you can’ afford it because it out of your budget, willingness is still their but it’s not effective in the market.
Consumer willingness to purchase should be backed by the dollars to create impact in the market.To be meaningful quantity demanded at certain price must be relate to specific time period – a day,week,month and year.”A consumer will buy 10 apples at $5 per apple” is meaningless. Saying “A consume will buy 10 apples per week at $5 per apple” is meaningful. Unless the time period is not mentioned it’s is impossible to determine whether the demand for the a product is huge and small.