Sabre is one of three main global distribution systems (GDSs) on the market, along with Amadeus and Travelport. GDS is a database of travel data pulled from various service providers that connect travel agents with hotels, airlines, car rentals, cruises, and railways. What used to be a manual system with each reservation taking up to 3 hours is now a global network. Sabre was the first of such GDSs. Basically, you can’t make the reservation process automatic without connection to this system.
You can use just one GDS – Sabre, for example – or a combination of a few, but if you specialize in only cruises or railways, research which GDS gives you a better shot at covering all providers. As you can see from the image below, Amadeus is an undisputed leader in everything but hotels, and with Sabre you’ll receive an average number of companies, only if you don’t want to cover all the cruises.