The magnet was not invented by man. It is a natural magnetite. The ancient Greeks and Chinese found in nature a naturally magnetized stone, called "magnet." The stone can magically pick up small pieces of iron and always point in the same direction when swung at will.
Early seafarers used the magnet as their first compass to navigate the sea. The earliest discovery and use of magnets should be Chinese, that is, the use of magnets to make "compass", is one of the four great inventions of China.
After thousands of years of development, today magnets have become a powerful material in our lives. By synthesizing alloys of different materials, the same effect can be achieved as magnets, but it can also increase the magnetic force.
Artificial magnets existed in the 18th century, but the process of making stronger materials was slow until the 1920s, when Alnico was created. This was followed by Ferrite in the 1950s and Rare Earth magnets (rare earth magnets include NdFeB and Samarium cobalt (SmCo)) in the 1970s. Since then, magnetic technology has developed rapidly, and strong magnetic materials have made components smaller.
The Earth itself has a very strong magnetic field, so people have a kind of adaptation and even dependence on the magnetic field. A weak and stable magnetic field is good for the body, and magnetic therapy is often used in medicine. Electromagnetic waves, on the other hand, are high-energy waves whose frequencies can have adverse effects on the body. So magnets are not harmful to humans.
