The (almost) horizontal line scanned by the electron beam in a video monitor. Also, the analogous line scanned by a video camera.
One sweep of a beam of electrons from left to right across a CRT display; also, one horizontal line of picture information in a video signal. In the NTSC system, each video frame is composed of 525 scanning lines (of which 480 are visible).
A horizontal line of pixels generated by a single horizontal sweep of the beam from a monitor's electron gun. The number of scanlines that make up a frame is the vertical resolution.