The emergence of wireless and mobile networks has made possible the introduction of electronic commerce to a new application and research subject: mobile commerce. Understanding or constructing a mobile commerce system is an arduous task because the system involves a wide variety of disciplines and technologies. To facilitate understanding and constructing such a system, this article divides a mobile commerce system into six components: (i) mobile commerce applications, (ii) mobile stations, (iii) mobile middleware, (iv) wireless networks, (v) wired networks, and (vi) host computers. Elements in components related to mobile commerce are described in detail and lists of technologies for component construction are also given.