 network are comparable to the output of other types of production facilities, market processes can allocate them. Markets refer to the interaction of buyers and sellers, 2 with market prices mediating between what buyers are willing to pay and what sellers are willing to accept. Market prices are determined through the activities of suppliers, customers, and intermediaries such as retailers and wholesalers. In the short run, firms raise prices when demand exceeds supply and lower prices when supply exceeds demand. In the long run, suppliers make production decisions by comparing the prices of goods to their costs and to the prices of alternative goods the supplier might provide. Firms will supply a good at some price if the cost of each unit provided and the cost at the margin (the last unit provided) are less than or equal to the market price. Classical economists, such as Adam Smith and David Ricardo, well understood that the deter- mination of market equilibrium prices and value results from the interaction of supply and demand, at least in the short run. The classical economists had various cost-based explanations for the determination of the long-run prices of land, labor, and capital. Beginning in the nine- teenth century, the marginalist revolution that led to today's neoclassical economy extended the supply-and-demand analysis consistently to output and input markets, in both the short and long run (Jevons 1879; Marshall 1898; Menger 1950; Walras 1954; Blaug 1968). On the role of intermediaries in market allocation mechanisms, see Spulber (1999). Pricing of Access to Networks Conversely, consumers make purchasing decisions based on the benefits that they derive from each good and the availability of substitute goods. Consumers will purchase a good at some price if the benefits of each unit consumed at the margin (the last unit consumed) equal or exceed the market price. The price will eventually adjust until the market clears, at which point supply and demand will be in balance and the benefits to consum