DOS, or Disk Operating System, is a type of operating system that manages computer hardware and software resources. It provides a command-line interface, allowing users to execute commands to perform tasks like file management, program execution, and system configuration. DOS was widely used in the early days of personal computing, particularly with IBM and Microsoft systems. The most well-known version of DOS is MS-DOS, developed by Microsoft. It played a crucial role in the development of early personal computers and laid the groundwork for more advanced operating systems. Although less common today, DOS is still used in some embedded systems and for specific applications requiring a simple interface.