Extended reality (XR) is an all-encompassing term that groups three similar technologies: (1) virtual reality (VR), (2) augmented reality (AR), and (3) mixed reality (MR). While XR is a field that has been in development in the U.S. Department of Defense (DoD) since the late 1960s, it has continued to see major advancements in recent years. This transformative technology has already made an impact across the DoD and holds considerable potential to improve the defense sector in the coming years.