Abstract: A system and method for customized advertisement selection and delivery on the World Wide Web (WWW) upon the Internet. The advertising system has a database server which stores advertisements and their campaign information, and an advertisement server which generates electronic advertisements available to a client system. In the system, a customization process which customized the electronic advertisements to be delivered to each client system is performed. A user connects to a web site and is presented with an editorial page or a list of search results. The system inserts a customized advertisement into the page that matches the page content or search topic. No identifiable data is collected during the interaction with the user. Advertisers can specify display constraints for each advertisement. The system will adapt all unrestricted parameters in order to maximize the user's click-through probability.