3 Guillermo Navarro Vicenç Torra 2009 The 28th North American Fuzzy Information Processing Society Annual Conference (NAFIPS2009) Cincinnati, USA IEEE 1-6 14/06/2009 978-1-4244-4575-2 privacy, microaggregation, Web mining An important trend for e-commerce sites is to be able to provide a personalized experience for the consumer, and there has been an increasing research interest in Web usage mining techniques to that end. One of the current problems of Web usage mining deals with privacy and anonymity. The data it uses, contains sensitive information that should be protected. We introduce the microaggregation of Web usage data to ensure its anonymity and privacy while maintaining its usefulness for usage mining.