(1) Ability to purchase Explanation: Need," "Want," and "Demand" are the three key concepts of marketing. Needs are the basic human requirements. These needs become wants when they are directed to specific objects that might satisfy the need, though these wants in themselves are not essential for living. Wants are therefore shaped by one's society and surroundings. The third concept, demands, are wants for specific products backed by an ability to pay. Many people want a luxury car or a weekend break in the Caribbean, but only a few people are willing and able to buy one.