In a theatre, on a computer screen, in a handheld mobile device, or in an AR headset, the angle from one edge of the view area to the opposite is commonly referred to as the angle of view or field of view (FOV). For example, a typical movie theatre screen is about 54 degrees; an IMAX theatre screen is 70 degrees. The human eye has about 160 degrees horizontal (monocular) or 200 degrees combined binocular FOV. The HTC Vive VR headset has about 100 degrees. Note that sometimes FOV is reported as separate horizontal and vertical; other times, it's a (better-sounding) diagonal measure.
Although not commonly discussed this way, when you hold a mobile device in front of you, it does have a field of view that is measured by the size ...
