Check out Craigs "Back to Basics with EDI 101" post at the Invois blog here: http://blogs.inovis.com/2008/09/11/back-to-basics-with-edi-101/ Craig covers the basics of EDI, why it exists, communications, and standards.  Its a great read for those new to the EDI world. Basically, at the core, EDI is a way of sending data back and forth between two entities. It can be two companies, two universities, or two hospitals; even two divisions of the same big company or corporation. EDI is used in a large number of industries - from retail sales and automotive manufacturing, to banks, hospitals, insurance and so many other industries and uses...