system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do magnets get demagnetised? How long does it take for that to happen?
gpt
Magnets depend on the orientation of the atoms in a material.  They will pretty much tend to stay that way.  But there are things that will de-magentize them. It's not simply a matter of a certain amount of time.  
   
Ways to de-magnetize:   
   
(a) Heat the magnet above its "Curie temperature".  That allows the atoms to have enough thermal energy to move into random orientations.   
   
(b) Wait a long time and let regular room temperature thermal energy do the same thing as (a).   
   
(c) Expose the magnet to a magnetic field that is in a different direction than the one it already has.    
   
(d) Whack the magnet with something hard or against something hard, repeatedly.   (Really, this works.)   
   
(e) A combination of the above.