An introduction to the new auction format known as 'Dynamic Alliance Auctions' which has been developed for Internet-based transportation marketplaces. The format allows for a packagewise placement of transportation orders even if these orders stem from different shippers. This, in turn, increases utilization of truck capacity and reduces risk for carriers. It also results in bringing down transportation prices without shrinking margins. After examining the landscape of Internet-based transportation marketplaces, the book identifies vital characteristics and needs of transportation business. The book shows how Dynamic Alliance Auctions combine ideas of matching theory, auctions and bargaining to fit these needs. Finally, the performance of this auction format is investigated analytically and experimentally using a modified private-value framework and different informational settings.