While the overall investment in information technology (IT) decreased somewhat during the first several years of the 21st century, B2B e-commerce technologies have expanded at an increasing rate (Lim & Wen, 2002). The expansion of B2B e-commerce has been technologically based on enterprise-wide information systems (EISs) that allow electronic data transmission and execution of transactions in a secure and efficient manner. Since B2B e-commerce is Internet-based, the EISs used to support B2B e-commerce must be Internet capable. The primary language of the Internet, Hypertext Mark-up Language (HTML), is not well-suited for transmitting data and executing transactions. Consequently, Extensible Mark-up Language (XML) was developed to facilitate electronic information exchange applications, including many applications related to B2B e-commerce. As initially conceived, XML had a number of constraints, particularly in the area of data integrity and security, however, these constraints have gradually been overcome. This chapter reviews the objectives of using XML in B2B e-commerce, reviews the technical structure of XML, and discusses ways that security and privacy can be enhanced while engaging in B2B e-commerce.