Microsoft Word is a word processor developed by Microsoft. It was first released on October 25, 1983[7] under the name Multi-Tool Word for Xenix systems.[8][9][10] Subsequent versions were later written for several other platforms including IBM PCs running DOS (1983), Apple Macintosh running the Classic Mac OS (1985), AT&T UNIX PC (1985), Atari ST (1988), OS/2 (1989), Microsoft Windows (1989), SCO Unix (1994), and macOS (2001).