This thesis investigates the concept of user experience, and how it is being used by researchers and practitioners working with the design or evaluation of interactive digital systems. It has as its aims to investigate the development of the understanding of the term over recent years, to characterize the field from the points of view of researchers and practitioners, and to investigate their level of collaboration and sense of a shared community. The main motivation for this inquiry is the perception that there exists a clear gap between industry and academia. In order to examine this, two studies have been performed. A systematic literature review of the academic literature on user experience from 1998 to 2017 has been conducted; 565 papers were categorized by how they address user experience, and what sources they reference. Trends were identified in both the selected papers and the referenced literature; the ten most cited papers were analyzed in more depth. Additionally, an interview study was conducted, with eight participants working with UX in industry and academia at various Danish companies and universities. Results from the two studies were cross-compared. The findings of the studies generally agree with previous research on the topic. A gap was clearly present among some researchers and practitioners, while others had ties to both industry and academia. In general, the two sides make limited use of each other's knowledge and literature. Education is found to be an important facilitator of collaboration. Regarding the concept of user experience itself, there is little agreement on a definition of the term. Despite many years of extensive research working towards a shared definition, there is still not a common understanding of the term. It is suggested that future work is done towards classifying and mapping the definitions that are in use, in order to explicate the patterns of understanding and take another step towards bridging the gap.