OTA stands for online travel agency. OTAs sell travel products like flights, hotels, and vacation packages on their websites. They work with global distribution systems and suppliers to provide inventory from airlines and hotels. When a customer books a hotel on an OTA site, the booking is not always instantly confirmed, as OTAs must check availability with partners. Comparison sites search multiple OTA sites at once but do not actually sell or book rooms themselves. OTAs often get better rates than going direct to hotels or airlines since they negotiate bulk deals.