Goods are physically tangible things such as food, shoes, cars and houses. Services are physically intangible things such as medical care, haircuts, and education. Goods and services must be produced.
Productive resources are the items necessary to make the goods and services that people want.
Scarcity is the condition of not being able to have all of the goods and services one wants. It results from the imbalance between relatively unlimited wants and the limited productive resources available for satisfying those wants. The price of a good or service reflects its scarcity. Opportunity cost is value of the best alternative given up when making a choice. There is an opportunity cost to every choice.