Abstract: The present invention provides a system, method, and applications for providing personalized user experiences based on the use of a core ontology and inferencing over the ontology using rules provided by a domain expert. The population of users may be known to a commerce or information service from external and internal user data sources. Information (data) about this population is brought into a knowledge warehouse designed for on-line analytic processing, and potentially data marts. Data can be sourced from external databases in batch or streaming mode and enhanced with real-time click stream events from internal observed user interactions. A reference ontology is either loaded into the system or defined via a domain expert. The ontology forms the central reference point for data enrichment and precise personalization. Characteristic data is tagged in accordance with direct reference to the nodes of the ontology and may be enhanced via inferencing techniques.