Ubiquitous Knowledge Discovery is a new research area at the intersection of machine learning and data mining with mobile and distributed systems. In this paper the main characteristics of the objects of study are defined and a high-level framework for analyzing ubiquitous knowledge discovery systems is introduced. Next, a number of examples from a broad range of application areas are reviewed and analyzed in terms of this framework. Based on this material, important characteristics of this field are identified and a number of research challenges are discussed. Ubiquitous Knowledge Discovery Knowledge Discovery in ubiquitous environments (KDUbiq) is an emerging area of research at the intersection of the two major challenges of highly distributed and mobile systems and advanced knowledge discovery systems. Today, in many subfields of computer science and engineering, being intelligent and adaptive marks the difference between a system that works in a complex and changing environment a...