Virtual Reality (VR) is the use of computer technology to create a simulated environment. Unlike traditional user interfaces, VR places the user inside an experience. Instead of viewing a screen in front of them, users are immersed and able to interact with 3D worlds.
Modern VR headsets fit under one of two categories: Mobile or tethered. Mobile headsets are shells with lenses into which you place your smartphone. The lenses separate the screen into two images for your eyes, turning your smartphone into a VR device.