Global distribution system  A global distribution system (GDS) is a computerised network system owned or operated by a company that enables transactions between travel industry service providers, mainly airlines, hotels, car rental companies, and travel agencies. The GDS mainly uses "real-time inventory" (e.g. number of hotel rooms available, number of flight seats available, or number of cars available) to service providers. Travel agencies traditionally relied on GDS for services, products and rates in order to provide travel-related services to the end consumers. Thus, a GDS can link services, rates and bookings consolidating products and services across all three travel sectors: i.e., airline reservations, hotel reservations, car rentals. GDS is different from a computer reservations system, which is a reservation system used by the service providers (also known as vendors). Primary customers of GDS are travel agents (both online and office-based) to make reservation on various reservation systems run by the vendors. GDS holds no inventory; the inventory is held on the vendor's reservation system itself. A GDS system will have real-time link to the vendor's database. For example, when a travel agency requests a reservation on the service of a particular airline company, the GDS system routes the request to the appropriate airline's computer reservations system. A mirror image of the passenger name record (PNR) in the airline reservations system is maintained in the GDS system. If a passenger books an itinerary containing air segments of multiple airlines through a travel agency, the passenger name record in the GDS system would hold information on their entire itinerary, each airline they fly on would only have a portion of the itinerary that is relevant to them. This would contain flight segments on their own services and inbound and onward connecting flights (known as info segments) of other airlines in the itinerary. e.g. if a passenger books a journey from Amsterdam to London on KLM, London to New York on British Airways, New York to Frankfurt on Lufthansa through a travel agent and if the travel agent is connected to Amadeus GDS. The PNR in the Amadeus GDS would contain the full itinerary, the PNR in KLM would show the Amsterdam to London segment along with British Airways flight as an onward info segment. Likewise the PNR in the Lufthansa system would show the New York to Frankfurt segment with the British Airways flight as an arrival information segment. The PNR in British Airways system would show all three segments.