The composition of magnets is iron, cobalt, nickel and other atoms, the internal structure of its atoms is relatively special, and it has a magnetic moment itself. Magnets can generate magnetic fields and have the property of attracting ferromagnetic substances such as iron, nickel, cobalt, and other metals.

　　Magnet is not invented by man, it is natural magnetite. Magnets can be divided into "permanent magnets" and "non-permanent magnets". Permanent magnets can be natural products, also known as lodestones, or artificially made (the strongest magnets are neodymium magnets). Rather than permanent magnets, they are only magnetic under certain conditions, usually in the form of electromagnets, which use an electric current to strengthen their magnetic field.

　　A neodymium magnet is also called an NdFeB magnet, its chemical formula is NdFeB, it is a kind of artificial permanent magnet, and it is the permanent magnet with the strongest magnetic force so far. The neodymium magnet was invented in 1982 by Mr. Sagawa and others from Sumitomo Special Metals Co., Ltd. It is known from its chemical formula that it is mainly composed of chemical elements such as neodymium, iron, and boron. Neodymium magnets with strong magnetic properties are widely used in electronic products, such as hard drives, mobile phones, headphones, and so on.

　　NdFeB magnets are the magnets with the highest commercial performance found at present. They are called the magnet king. They have extremely high magnetic properties and their maximum magnetic energy product (BHmax) is more than 10 times higher than that of ferrite. Its own machining performance is also quite good. Operating temperature up to 200 degrees Celsius. Moreover, its texture is hard, its performance is stable, and it has a good price/performance ratio, so it is widely used. But because of its strong chemical activity, its surface layer must be treated.