Quark Xpress is a page layout software programme. Quark helped spark the revolution in desktop publishing with the 1987 release of QuarkXPress®. Desktop publishing was in its infancy, and most publications were produced mechanically. QuarkXPress introduced precision typography, layout, and color control to the desktop computer. According to Quark there are now more than three million QuarkXPress users worldwide. Quark had enjoyed a virtual monopoly in the desktop publishing market for many years with some competition in the early years coming from Aldus Pagemaker and Adobe FrameMaker, Pagemaker lacked some key features, like the ability to produce seperations and FrameMaker became more of a niche product more suitable for producing technical documents and manuals. By version 5 Quark seemed to have lost interest in producing a competitive product; well there was no competition, however Adobe released InDesign which was the first DTP programme to become available for Mac OS X. By version 7 Quark had started re-invent itself (it started to lose considerable market share to InDesign) with a more open approach to it's customers and some long awaited features. The currently version is 8 which is considerably more stable and quicker than version 7 and handle file imports considerably better (particularly PDF's).
UPDATE Quark Xpress 9 arrives:
Recently Quark released version 9, many new features seems to large focused on either creating Flash animation, ePublishing, and iPhone / iPad App creatation (in reality the App creation is a pretty narrow focus and in my opinion it's more of an eBook publishing solution than a programming tool). Having said that many of us will be glad to have a good solution to port print content to iPad and other tablet devices without the headache of re-design and reflowing content.