The document discusses the top 5 B2B marketplaces from January to March 2012. WorldofTrade.com is identified as the number 1 B2B portal, offering business solutions to buyers and sellers globally. Alibaba is described as a privately owned Chinese e-commerce company that operates multiple platforms for B2B trade, retail, and other services. BusyTrade.com is highlighted as one of the pioneering online trading platforms in China and Asia. TradeKey.com and Asia Net are also listed among the top B2B marketplaces.