Key Elements of Demand:

1. Willingness to Buy: Consumers must want the good or service.
2. Ability to Pay: Consumers must have the financial means to purchase the good or service.
3. At Different Prices: Demand varies depending on the price of the good or service. Typically, demand decreases as the price rises (law of demand).

Example:

If the price of a coffee cup is $5, consumers might want to buy 100 cups per day. However, if the price drops to $3, they might be willing to buy 150 cups per day. This variation in quantity based on price is a key aspect of demand.

Thus, demand is a relationship between price and the quantity demanded, where lower prices typically lead to higher demand, and higher prices result in lower demand, all else being equal.