That depends on the program you used to backup, the medium backed up to (cloud, USB-stick, external disk, cd, dvd) and the file system of the medium.
That's about getting an exact copy. It depends on the file type if you can use it in Windows.
Kees
How would you restore files used from an Apple backup onto PC with either Windows 7 or Windows 8? Where there be any compatibility issues at all?

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