To demagnetize something means to remove its magnetic properties, making it stop attracting metal objects like iron or steel. When you demagnetize a magnet, it loses its ability to pull paper clips or stick to your refrigerator.

This happens because magnets work by having their tiny internal particles aligned in the same direction, like soldiers standing in neat rows. When you demagnetize something, you scramble this alignment. You can demagnetize a magnet by heating it, striking it repeatedly with a hammer, or exposing it to a strong alternating magnetic field that essentially confuses and randomizes those internal particles.

Sometimes demagnetization is useful. Credit cards and hotel key cards can accidentally become demagnetized if they sit too close to magnets, which can erase the information stored in their magnetic strips. Repair shops use special tools to deliberately demagnetize screwdrivers and other metal tools that have become magnetized through use, since magnetized tools can attract metal shavings that get in the way during delicate work.