Also known as V4L
Video4Linux is the framework for drivers for video cameras, TV tuners etc. There is an API to use these devices. This is commonly called v4l or v4l2 (v4l being deprecated in theory)
Devices that use this framework are normally compiled into the LinuxKernel as Modules.
Devices are enumerated by UDev and appear as /dev/video0, /dev/video1 etc.
12 pages link to Video4Linux:
