In beginning our discussion of the various legal instruments used in assembling funds for the purchase of rights in land and improvements in a real estate market, it will be well to note that, in the case of a fee, the estate purchased is in this perpetuity. This affects the price, which is customarily paid in advance for the perpetual term, and contrasts sharply with transactions involving short-term estates, such as apartment or office leases. It is also the reason why most real estate financing problems arise out of transactions in real estate market involving fees.