The success of e-commerce is based on standards, such as TCP/IP and HTTP, as well as low-cost Internet access. But more important, its triumph lies with the protocols involved in exchanging money for goods and services. These payment protocols define electronic commerce, distinguishing true e-commerce sites from their information-only, “brochureware” counterparts. A payment protocol does not move data; it moves money. The headers and provided services of these protocols are layered on top of underlying data- and link-layer protocols.