WUM: A Web Utilization Miner. Most web sites are set up with little knowledge on the navigational behaviour of the users accessing them. Feedback on the occurring navigation patterns can significantly aid site owners in efficiently (re)organizing the hyperspace they present to their visitors. In this study, we present the Web Utilization Miner WUM, a mining system for the discovery of interesting navigation patterns. The interestingness criteria for navigation patterns are dynamically specified by the human expert using WUM’s mining language MINT. MINT supports the specification of criteria of statistical, structural and textual nature. To discover the navigation patterns satisfying the expert’s criteria, WUM exploits an innovative aggregated storage representation for the information in the web server log.