The world is witnessing a continuous expansion of electronic commerce into the global digital economy. As an enabler of new businesses, Web-based shopping systems (WBSS) are at the heart of the major issues surrounding electronic commerce growth. Their wide use has profoundly altered the ways in which businesses and customers, and businesses and businesses interact on the basis of digital transactions. Despite the importance of WBSS, the theoretical study of their strategies has been sparse. This article offers a theoretical analysis of evolutionary processes in WBSS strategies. For that purpose, we propose a classification model of WBSS. Based upon the model, WBSS are classified into four types: (1) general-direct-sales (GDS); (2) general-intermediary-sales (GIS); (3) specialized-direct-sales (SDS); and (4) specialized-intermediary-sales (SIS). On the basis of these four categories of WBSS, we analyze the characteristics of WBSS and suggest five evolution strategies for WBSS, which have implications for both theory and practice. Amazon.com's strategic movements, such as product line expansion through alliance and acquisition, provide an exemplary case of the evolution of WBSS strategy. We expect that this article will serve as a guide for Internet businesses and as a catalyst for new research agendas relevant to web-based shopping and electronic commerce.