Microsoft Word is a word processing software developed by Microsoft. It was first released on October 25, 1983, under the name Multi-Tool Word for Xenix systems. 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 (1990) and macOS (2001). Using Wine, versions of Microsoft Word before 2013 can be run on Linux.

Commercial versions of Word are licensed as a standalone product or as a component of Microsoft Office suite of software, which can be purchased either with a perpetual license or as part of a Microsoft 365 subscription.