What is an electromagnetic degausser?

Degausser is a device which is used for destroying data stored in computers and laptop hard disks, floppy disks and backup tapes. During degaussing process, it generates powerful magnetic field by charging capacitor and then changing the alignment of magnetic domains on the magnetic storage media by discharging.

After such degaussing, many forms of generic magnetic storage media can be reused, including reel-to-reel audio tape, VHS videocassettes, and floppy disks. But for certain computer data storage media, however, such as modern hard disk drives and some tape drives, degaussing renders the magnetic media completely unusable and damages the storage system.For all form of magnetic storage media, the data storage in them can not be retrievably any more.