Final answer:
Demand refers to the amount of goods or services consumers are willing and able to purchase at each price. It is based on needs and wants, and is influenced by the ability to pay. A homeless person, for example, may have no effective demand for shelter if they cannot afford it.
Step-by-step explanation:
Demand for Goods and Services
Economists use the term demand to refer to the amount of some good or service consumers are willing and able to purchase at each price. Demand is fundamentally based on needs and wants-if you have no need or want for something, you won't buy it. While a consumer may be able to differentiate between a need and a want, from an economist's perspective they are the same thing. Demand is also based on ability to pay. If you cannot pay for it, you have no effective demand. By this definition, a homeless person probably has no effective demand for shelter.