An aggregator travel site allows users to search across multiple online travel agencies (OTAs) to find the best rates for flights and hotels. The document compares Mobissimo and Yahoo! Travel, two major aggregator sites. Both sites search across many OTAs to display results but Mobissimo focuses more on Europe while Yahoo! Travel has a broader international reach. The document also lists the OTAs and travel partners included in each site's searches to provide users the most comprehensive comparison of rates.