As with so many major standards, ISO 9000 began life as a BSI publication. In this case, BS5750. It actually has a very interesting history, stemming back to the need to apply common procedures to prevent accidental detonations in weapons factories during Word War II. The number 9000? One might assume that this stems from the number used by BSI for their related quality standard for the electronics industry, BS9000.
Since the, ISO 9000 has been revised a number of times. The first version was published in 1987. Major revisions, and extensions, however, came in 1994 and 2000.
The ISO 9000 series actually comprises a number standards, the most significant of which is perhaps ISO 9001 ( Quality management systems - Requirements ). This is the standard against which formal certification is offered.