We say that a thing is good if it serves as a means to a desired end or purpose. We may therefore define a good as a thing which satisfies a want. Many of our wants are satisfied by goods which exist in such plenty that we need not give a thought to securing them. Thus, the air we breathe and the water we drink are free gifts of nature. We can obtain them without the exertion of conscious effort. We call such things free goods.

On the other hand a great many of our wants are gratified by goods which are limited in quantity in comparison to the wants to which they minister. As a usual thing such goods can be had only by the expenditure of effort. Goods which are scarce, that is, limited in relation to the wants which they gratify, are called economic goods. Personal services gratify wants, and are therefore, strictly speaking, goods. Free goods, as distinguished from economic goods, are not wealth.