A payment for the services of a factor of production which in the medium term is similar to rent. Whereas rent is paid for the services of land, which is provided by nature, quasi-rent is paid for the services of factors which owe their qualities to past sunk investment. It behaves like rent because in the short run the factors would not disappear if the payments were decreased. These payments are not true rents, since in the long run they have to be sufficient to induce new investment, for example, renewing buildings or paying for professional training.