CRS stands for Computer Reservation System. A computer reservation system is a computerized system used to store and retrieve information and conduct transactions related to air travel. Originally designed and operated by airlines, CRS's were later extended for the use of travel agents major CRS operations that book and sell tickets for multiple airlines are known as global distribution systems (GDS). Airlines have divested most of their direct holdings to dedicated GDS companies, who make their systems accessible to consumers through internet gateways. Modern GDS's typically allow users to book hotel rooms and rental cars as well as airline tickets