(Electronic Data Interchange) Pre-Internet form of e-commerce. Governed by rules maintained by the United Nations, EDI set out to formalize electronic commerce as a set of standardized message formats, by which businesses would exchange documents such as purchase orders and invoices with each other electronically. Until the advent of the Internet, EDI messages had to be exchanged via dedicated Value-Added Networks (VANs). This restricted its use to large corporations who had the clout to impose EDI standardization on their supply chain partners. It is gradually being absorbed into (or, depending on your point of view, superceded by) XML-based equivalents.