DOC, Doc, doc or DoC may refer to:

• Doc (2001 TV series), a 2001–2004 PAX series
• Doc (1975 TV series), a 1975–1976 CBS sitcom
• "D.O.C." (Lost), a television episode
• Doc (film), a 1971 Western film
• Documentary Organization of Canada, known as DOC, a non-profit organization supporting documentary filmmakers in Canada
• Doc Films, a University of Chicago film society

Dóc is a village in Csongrád county, in the Southern Great Plain region of southern Hungary.

In computing, DOC or doc (an abbreviation of 'document') is a filename extension for word processing documents, most commonly in the proprietary Microsoft Word Binary File Format. Historically, the extension was used for documentation in plain text, particularly of programs or computer hardware on a wide range of operating systems. During the 1980s, WordPerfect used DOC as the extension of their proprietary format. Later, in 1983, Microsoft chose to use the DOC extension for their proprietary Microsoft Word format. The original uses for the extension have largely disappeared from the PC world.

M-Systems Ltd., (sometimes spelled msystems) was a Nasdaq-listed Israeli producer of Flash memory storage products founded in 1989 by Dov Moran and based in Kfar Saba, Israel. They were best known for developing and patenting the first flash drive, marketed in 1995 as DiskOnChip, and the first USB flash drive, marketed in 1999 as DiskOnKey. They also created the patented True Flash Filing System (TrueFFS) which presented the flash memory as a disk drive to the computer. After 17 years of business, they were acquired by their prior competitor, SanDisk, in 2006. The DiskOnChip (DOC) was developed at the R&D Center established by M-Systems called EUROM. Rick Iorillo, Rony Levy and David Deitcher were the individuals that worked on the development and marketing of the first 2 MB DOC. This product went on to receive the Most Innovative Award from EDN in 1995 and later went on to become the Flash Drive and DiskOnKey.