Degauss
Degauss describes a method of erasing magnetic media by passing it through a strong magnetic field. This process destroys any data on a magnetic storage device. Degaussing is named after Johann Gauss, a mathematician who studied and worked with electromagnetic fields.
Degaussing CRT monitors
Degaussing is also used with CRT (cathode ray tube) monitors to fix possible color impurities. After the degauss button is pressed, the degaussing circuit is activated and deactivated after a few seconds. Older monitors that didn't include this feature had to be degaussed using a handheld device.
What is a degausser?
A degausser is a demagnetizing device used for erasing all data from the read/write heads of different storage drives.
History
The British Royal Navy first used degaussing in the 2nd World War. An electromagnetic cable was inserted inside and around each warship to safeguard against magnetic mines. Each time a ship came into the harbor, it was degaussed using said cable. This process worked by passing an electrical current through the cable to neutralize the magnetic field, causing the mine to detach.