BUSINESS-TO-BUSINESS ELECTRONIC COMMERCE (B2B EC) has emerged as the largest pie in EC. However, its definitions as well as perspectives on the current status and future prospects are not unequivocal. Therefore this article describes the necessary factors that can enhance the effectiveness and efficiency of the electronic commerce between companies. Then the current key activities in the B2B EC area are reviewed one by one with the discussion of its relationship with others. Key activities included are B2B e-marketplaces (seller, intermediary, or buyercentric ones); on-line service applications for business; the electronic procurement management system and its integration with external e-marketplaces; evolution of the EDI platform onto the Internet; collaboration by supply chain management; the shared data warehouse and virtual corporation; agent-based commerce between the buyer agents and seller agents; XML (eXtensible Markup Language) standards and their integration with electronic data interchange (EDI) and agents. This article provides a good understanding about activities in the B2B EC area, and explicates the converging phenomena among the separate activities toward enhanced managerial performance.