A file critical to the proper function of an operating system which, if deleted or modified, may cause it to no longer work. Often these files are hidden and cannot be deleted because they are in use by the operating system. A system file is also an attribute that can be added to any file in Windows or DOS using the .sys file extension. Although this process allows the operating system to know the file is important, it does not make the file a system file.
File, Hidden file, MS-DOS, Operating system terms, Windows
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