DOS

DOS is a class of disk operating systems that manage files and programs through command-line interfaces, typically on personal computers.

Command-line interface: A text-based interface in which users enter commands to control a computer. DOS commonly accepts commands through a text prompt rather than a graphical desktop.
CP/M: A disk operating system for early microcomputers, widely used before the IBM PC era. CP/M established conventions that shaped expectations for personal-computer disk systems.
MS-DOS gaming: Video games designed to run under Microsoft's DOS operating system. DOS became a major platform for PC games before Windows dominated consumer computing.
Microsoft Windows: A family of operating systems with a graphical desktop interface, developed by Microsoft. Windows grew from a graphical environment running alongside DOS into a separate operating-system family.
Command interpreter: A program that reads commands, interprets them, and starts requested operations. The DOS shell parses typed commands and launches built-in functions or programs.
86-DOS: A 16-bit operating system created by Seattle Computer Products for its Intel 8086 computers. Microsoft acquired 86-DOS and adapted it into the system supplied for the IBM PC.
Lotus 1-2-3: A spreadsheet program that became a leading business application for IBM-compatible PCs. Its success helped establish DOS computers as practical tools for office work.
Unix: A family of operating systems developed around multitasking, multiuser access, and portable design. Unix offers capabilities such as multiuser operation that classic DOS was not built to provide.
FAT file system: A file system that records file locations in a table of allocation units. Many DOS versions use FAT to organize files and directories on disks.
Microsoft Disk Operating System: Microsoft's family of DOS operating systems, commonly known as MS-DOS. MS-DOS became the best-known DOS family and influenced compatible systems.

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