A Disk Operating System, or DOS, is a type of operating system that manages computer hardware and software resources. It provides a user interface for executing commands and running programs, primarily through a command-line interface. DOS was widely used in the early days of personal computers, allowing users to perform tasks like file management and program execution. The most well-known version of DOS is MS-DOS, developed by Microsoft. It played a crucial role in the development of personal computing in the 1980s and 1990s. Although modern operating systems have largely replaced DOS, its influence can still be seen in contemporary command-line interfaces.