In the last years, the world wide web has not only been exploited for disseminating information but also, companies use it to improve their interaction with customers, distributors, suppliers and partners. This way of conducting business using the Internet is known as electronic commerce (e-commerce). Broadly defined, electronic commerce is a modern business methodology that addresses the needs of organizations, merchants, and consumers to cut costs while improving the quality of goods and services and increasing the speed of service delivery [KW96]. The term e-commerce is used to describe a new on-line approach to performing traditional functions such as payment and funds transfer, order entry and processing, invoicing, inventory management, cargo tracking, electronic catalogs, point-ofsale data gathering, advertising and marketing.