Magnet is not human invention, there are natural magnetite, the earliest discovery and use of the magnet should be Chinese. So "compass" is one of the four Chinese inventions. As for the composition that is iron, cobalt, nickel, etc. Its atomic structure is special, the atom itself has a magnetic moment .In general, these mineral molecules arranged in chaos. Magnetic field can not show each other magnetic .. But under the external force (such as magnetic field) guided The iron is the most commonly used magnetic material is basically the magnetic sub-permanent magnet and the soft iron permanent magnet is coupled with strong magnetic to magnetic material spin and electrons. Angular momentum into a fixed direction of the arrangement of soft magnetic is coupled with the current (also a method of adding magnetic force) and other current to remove the soft iron will slowly lose the magnetic As for the earliest magnet who found the oldest record is the Chinese Huangdi war Chi's guide car So called one of China's four major inventions! China in the first century BC that is known to have the case of magnet polarization. Warring States period, had to use a natural magnet, on the scale of the copper plate, used to divination. The Northern Song Dynasty, the use of two methods to create artificial magnets, one is to burn red iron needle, placed in the north-south direction, rapid cooling, the use of the Earth's magnetic field will be iron needle magnetization; the other is made of magnet rubbing iron needle The "Mengxi Bi Tan" recorded in the presence of magnetic declination, found under the influence of magnetic declination, the magnetic needle pointing to the south, slightly more than the real south. Based on this knowledge, the development of the magnet as a compass of the scientific application. Magnet is only a generic term, is generally refers to the magnetic things, the actual composition does not necessarily contain iron. The pure metallic state of the iron itself is not permanent magnetic, only close to the permanent magnet will be induced to produce magnetic, the general permanent magnet which added other impurity elements (such as carbon) to stabilize the magnetic, but this will make the freedom of electrons Lower and easy to conductive, so the current through the light when the lamp does not light up. Iron is a common magnetic element, but many other elements have a stronger magnetic, like a lot of powerful magnets is ruby iron and boron mixed.