Virtual Reality (VR) is a computer-simulated, three-dimensional environment that can be explored and interacted with by a person via a human-machine interface device. VR technologies have been applied to a broad range of fields, including video games, flight training, combat training, and surgical training. This report provides an overview of VR technologies, together with their major sectors, fields, and applications. Meanwhile, a US startup company has received a patent related to head-mounted VR goggles with the use of a mobile computing device in late 2015. Against the backdrop, whether other vendors, particularly Google's Cardboard and Samsung's Gear VR will infringe on that patent is also discussed in this report.