A Value-Added Network (VAN) is an electronic post office that routes transaction files from one subscriber to another, much like email. VANs may also perform file format and protocol translation, archival and other services, which is why they are referred to as value-added networks.

The use of VANs to transmit ANSI-standard X12 electronic data interchange (EDI) transactions is a long established and highly reliable method of conducting machine-to-machine business. The DOD makes substantial use of EDI in its day to day operations, operating several of its own VANs, with which DOD-certified VANs interchange data. The DoD VANs, called Network Entry Points, were left out of the picture at right for simplicity. See this detailed illustration for more information.

In order to exchange data with the DOD, Value-Added Networks go through a rigorous annual review process which grants them authorization for data interchange. Such VANs are often referred to as DOD-certified VANs, although that is not completely accurate. The Mil-Pac VAN is an example of such a service.