Learn in the textbookOutput Devices (Display and Printing)
DefinitionA head-mounted display (HMD) (ヘッドマウントディスプレイ) is a display device worn on the head that shows images on a small screen in front of the eyes.
ExplanationPaired with sensors that detect which way the head faces, it switches the image to match the direction you look. It serves as a device for VR (仮想現実, virtual reality), which fills your view with images, and for AR (拡張現実, augmented reality), which lays information over the real scene.
AnalogyMuch as the view beyond a binocular's small lenses looks huge, a small screen placed right before the eyes fills most of your view and looks large.
Memory hookBreak the English apart: a display you mount on your head, and where it goes is plain to see.