WorPerfect is a proprietary word processing application. At the height of its popularity in the late 1980s and early 1990s, it was the de facto standard word processor, but has since been eclipsed in sales by Microsoft Word. Although the MS-DOS and Microsoft Windows versions are best known, its popularity was based on the fact that it had been available for a wide variety of computers and operating systems, including Mac OS, Linux, the Apple IIe, a separate version for the Apple IIgs, most popular versions of Unix, VMS, Data General, System/370, AmigaOS, Atari ST, OS/2, and NeXTSTEP.