User experience, commonly abbreviated UX, is a ubiquitous term in human-computer interaction, yet the term carries different semantics and connotations to practitioners across the field. While the exact definition of the term has been hotly debated in academic circles, the modern view appears to be largely divided into two, complementary, approaches: One that recognizes that User Experience is a collection of theory, methodology and practice from a number of disparate scientific disciplines, all with the same overarching aim of studying the experiential aspects of human interaction with technological artifacts; and another that uses such theory, methodology and practice integrated in the design of such technological artifacts, typically under the slogan User Experience design. While the academic debate of an exact definition of, and foundation for the principles of, User Experience still generates discussion, this chapter aims at giving an overview of extant views of User Experience with particular attention to the multi-faceted and multi-disciplinary nature of the subject as used by researchers and practitioners in the field.