Permanent magnets can probably be a natural product, known as lodestone to be made about artificial (NdFeB magnets are the strongest magnets).

Non-permanent magnets is heated to a certain temperature suddenly loses its magnetism, which is due to voluminous composition magnet "meta magnet" points column from order to disorder caused by; magnet loses its magnetism put into a magnetic field, when the magnetization strength reaches a certain value, it is magnetized, "yuan magnet" of the breakdown and from disorder to order.

In fact, outside of permanent magnet permanent magnet elements will not tamper with it not only the high temperature magnetic, impact will it loses its magnetism, the strong magnetic field can also probably tampered with its poles and its magnetic strength, with the exchange of electricity produced by breeding size change soon magnetic field can probably give non-magnetic material demagnetization of permanent magnets do not show it ferrite magnetic tile