Rent is the payment which is made for the use of land and other natural agents. Popularly, a clear distinction is not always made between rent and interest; thus, we sometimes speak of the income which a person receives for his investment in land as interest on his investment instead of calling it rent. Likewise, when we speak of the return which is made for the use of specific pieces of capital goods, we often refer to it as rent. Thus, we speak of rent for a house or a boat or a horse. But since we are going to distinguish between the income received by the owners of the land and that received by the owners of capital, it will be useful, instead of referring to these incomes indiscriminately as rent or interest, to call the one rent and the other interest. Economists have pretty generally adopted this custom referring to the income from land as rent and to the income from capital as interest.