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 Widows 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.
Tip: If you are looking for help about a system file and know its name, try using the search function.