Booking is the world’s largest online travel agency by sales, offering booking and payment services for hotel and alternative accommodation rooms, airline tickets, rental cars, restaurant reservations, cruises, experiences, and other vacation packages. The company operates several branded travel booking sites, including Booking.com, Agoda, OpenTable, Rentalcars.com, Kayak, and Momondo. Transaction fees for online bookings account for the bulk of revenue and profits.