HD - technical definition

(1) (High Definition) Refers to many different formats over the years for video cameras and camcorders, both analog and digital, that exceeded the resolution of analog TV (NTSC, PAL). In 1998, the U.S. introduced an official set of digital TV standards that included HD (see HDTV and DTV). See also high-def DVD formats, HD Radio, HD Audio and HDV.

(2) (Hard Disk or Hard Drive) The HD acronym is widely used in drive specifications; for example, 80GB HD means 80 gigabyte hard disk. FD means floppy disk. See magnetic disk and HDA.

(3) (High Density) The official designation for the most common floppy disk formats. For example, the 1.44MB 3.5" floppy was HD in contrast to the earlier 720KB format, which was DD (double density). For 5.25" floppies, the 1.2MB version was HD; the earlier 360KB was DD. See floppy disk.