Why is it necessary to protect floppy disks from magnetic fields in order to preserve information?

Because floppy disks (floppy disks) are not shielded from magnetic fields in any way. enclosed in a plastic container. Accordingly, a more or less strong magnetic field (for example, from a permanent magnet) can affect the magnetic charges of the tracks on the disk, distorting the information there in binary form. This will lead to reading errors, i.e. useful information on the floppy disk will be lost: archives will be “broken”, the program will stop running, etc.