A global distribution system (GDS) is a network operated by a company that enables automated transactions between third parties and booking agents in order to provide travel-related services to the end consumers. 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, and activities.
GDS is different from a computer reservations system, which is a reservation system used by the respective vendors. Primary customers of GDS are travel agents (both online and office-based) to make reservation on various reservations 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, the GDS system routes the request to the appropriate airline's computer reservations system. This enables a travel agent with a connection to a single GDS to choose and book various flights, hotels, activities and associated services on all the vendors in the world who are part of that GDS.