A head-mounted display (HMD) is a display device, worn on the head or as part of a helmet, that mounts either a single screen in front of both of the users eyes (monocular HMD) or a separate screen in front of each eye (binocular HMD). An extensive summary of the properties of VR HMDs is available on the XinReality wiki or on Wikipedia. HMD's are generally either "tethered" (such as Oculus Rift) to a PC that monitors tracking and undertakes the rendering, or "untethered" (such as Oculus Quest) where the unit is standalone.
HMD Name
Supported Runtimes
Oculus Rift CV1
Oculus Runtime; SteamVR
HTC Vive
SteamVR; Oculus Runtime (via Revive)