Transhumanism is an intellectual and cultural movement that advocates using existing, emerging, and speculative technologies to enhance humans beyond current natural limitations, particularly by extending longevity and improving cognition, health, and well-being. Drawing on developments in science, technology, engineering, and mathematics (STEM), as well as longstanding themes in science fiction, transhumanism explores the ramifications, promises, and potential dangers associated with human enhancement technologies. Key areas of inquiry include nanotechnology, biotechnology, information technology, and cognitive science (NBIC). Transhumanists envision that the convergence of advanced human enhancement technologies could eventually enable humans to become "posthumans", beings whose capacities exceed those of present-day humans. Some transhumanists focus on conceiving strategies for reducing existential risks to humanity, including those posed by artificial superintelligence, asteroid impacts, gray goo, nuclear warfare, pandemics, and societal collapse.