A system and method for conducting commerce over a distributed network manage merchant and product information in an electronic shopping basket, payment source information in an electronic wallet, and shipping address information in an electronic address book, all of such information being stored on a consumer computer. A commerce client running on the consumer computer is configured as a MIME handler and extends the functionality of a standard Web browser to support computer-based shopping. A merchant site Web server provides HTML-coded Web documents which describe merchant products and which host computer-based shopping options. The HTML-coded Web documents contain function-calling information by which consumer-selected options invoke shopping-related functions on either the merchant (server) computer or the consumer (client) computer. A consumer selects the options from within the Web browser to initiate shopping-related operations such as: retrieve product information from merchants on the World Wide Web, selectively store product information locally on the consumer computer, locally compare product information from different merchants, locally store payment source and shipping address information and selectively forward such information to merchant sites, order products from Web-based merchants, track the status of purchase orders, and receive instructional information on application usage.