A Global Distribution System (GDS) is a vital reservation tool used by travel agencies for booking flights, hotels, and car rentals, integrating services and pricing across the travel industry. Major GDS providers include Travelport, Amadeus, Galileo, and Sabre, each offering features such as real-time inventory control and extensive market reach. Travelopro specializes in GDS software development, providing solutions for various business models and integrating travel APIs for comprehensive booking services.