Mind-wandering was until recently not a mainstream topic of research. The aim of this literature review is to present current views on the definition of mind-wandering and how the phenomenon is experienced. Furthermore, it gives an account of the implications of mind-wandering on cognitive performance, as well as its neurological correlates. In addition, the methods used to study mind-wandering are reviewed.The study of mind-wandering reveals a highly frequent phenomenon with practical consequences on a broad scale, both disruptive and supportive to goal-related behaviour and wellbeing in general. Originating from the default network, and its regions related to representations of self, memory, Theory of Mind, empathy and creativity, mind-wandering is hypothesized to be a function for planning one’s future life. Suggested further research concerns how mind-wandering can be countered, detected from the outside and whether it alters the physical feature of the brain.