Travel Data Interchange is the interchange of strictly formatted messages, representing documents that differ from monetary instruments. It implies a succession of messages between two co-operating parties, with one of them serving as originator and other as recipient. The data representing the documents can be either transmitted via telecommunications, or transported physically on electronic storage media.

With Travel Data Interchange, the processing of received messages is possible only by computer, while the human intervention is intended only for special situations, like quality review or error conditions. As an example of Travel Data Interchange we can speak about a set of interchanges between a seller and a customer. Messages from customer to seller can include purchase order, receiving and payment advice and request for quotation among others, while messages form seller to customer usually comprise purchase order acknowledgement, invoice and shipping notice. These messages can either provide information and advice, or they may have legally binding obligation, like bid in response to purchase order.

Currently Travel Data Interchange is used for a diverse set of concerns, such as hotel and travel bookings, transportation, education administration and more.
Implementation of Travel Data Interchange requires the use of interrelated standards, which include the syntax for composing messages and separating various message parts; definitions and types of application data elements; the message types, defined by sequence and identification of data elements that form each message; and the definitions of control data elements in message headers. Additional standards may comprise a set of data segments; the manner in which several messages can be included into a single transmission; and the manner of using protective measures for confidentiality and integrity of transmitted messages.

A set of adopted standards was developed by a number of organizations, including Accredited Standards Committee X12 on Electronic Data Interchange, Health Level Seven Inc., and the UN/EDIFACT standards by the UN Economic Commission for Europe.

The United Nations/Electronic Data Interchange for Administration, Commerce and Transport, commonly known by its acronym UN/EDIFACT, is the internationally designed EDI standard, developed under the United Nations. The further development and maintenance of this standard is done through the United Nations Center for Electronic Commerce for Administration, Commerce and Transport, under the UN Committee on Trade, Economic and Social Council. It has been adopted to provide a set of syntax rules to structure data and standard messages.

There are two major organizations dealing with EDIFACT, namely Travel Tourism and Leisure and Passenger and Data Interchange Standard. EDIFACT transmissions are divided into elements, messages and segments.

UN EDIFACT messages are used as an alternative to teletype messages in the airline industry.