[[First the top left of the back of the floppy there is a small tab. This
tab enables the floppy disk to be switched from write protected and un-write
protected. Move the tab to the top position creating a hole makes the disk
write protected. This means that nothing can be written, erased or deleted
from the diskette. Moving the tab to the bottom position allows the disk to
be un-write protected. Which means the diskette can be written too, erased
and or have information deleted from the diskette.]] http://www.computerhope.com/help/floppy.htm