One of the factors of production, with land, capital and enterprise. Among the things that determine the supply of labor are the number of able people in the population, their willingness to work, labor laws and regulations, and the health of the economy and firms. Demand for labor is also affected by the health of the economy and firms, labor laws and regulations, as well as the price and supply of other factors of production. In a perfect market, wages (the price of labor) would be determined by supply and demand. But the labor market is often far from perfect. Wages can be less flexible than other prices; in particular, they rarely fall even when demand for labor declines or supply increases. This wage rigidity can be a cause of unemployment.