HotStart

Windows HotStart is a feature introduced with Windows Vista which allows users or OEMs to assign a specific key or button to a specific application.[1]

When pressed, this button or key can turn on the computer (must be supported by the hardware) which will then automatically boot to a basic mode of Windows without Desktop which loads only the predefined application besides drivers and necessary runtimes without having the need to logon or wait for the Desktop to load.

These buttons were commonly used by manufacturers to enable a HotStart to a DVD-Player.