Question: how do magnets work?

Robert Woolfson answered on 21 Jun 2013:

Magnets work based on the way electrons inside the material behave. Magnets such as fridge magnets, which are permanent magnets, have all the electrons line up in the same direction which produces a strong permanent magnetic field. This is called ferromagnetism

There are other types of magnets, called antiferromagnets, where the electrons line up in opposite directions and which show very different behaviour. Then there’s electromagnets, which are temporary and only work when an electric current is put to them.

Also, take a look at this link for when magnets go wrong. Just to be clear, this is very rare and almost never happens. MRI machines are perfectly safe.