Highways, railroads, pipelines—we see or hear about these types of physical networks almost every day. But information systems, such as the Internet, and payment systems, such as ATMs and credit cards, also involve networks. Hence, understanding the economics of networks and the unique...

To become an active market in goods and services, the Internet must overcome a fundamental hurdle: a way must be devised for buyers and sellers to securely and conveniently exchange payment over the Internet. Software companies and financial institutions are now developing methods that will...