The concept of "market price" is associated with the very short period, also known as the market period. In this time frame, the supply of a commodity, especially perishable goods, is considered fixed. Because producers do not have enough time to alter the level of production in response to changes in demand, the price is determined primarily by the prevailing demand conditions. This day-to-day price, which can fluctuate significantly, is the market price. In contrast, the "normal price" is the price that tends to prevail in the long period, where supply can fully adjust to demand.