Permanent magnets can be made from many different materials with varying qualities. Each material has distinct strengths and weaknesses in four different categories of magnetism. These four categories are remanence, coercivity, energy product and Curie temperature. There are also four main types of materials for making permanent magnets. These are ferrite, alnico, samarium cobalt and neodymium magnets.
The strongest permanent magnets are those made of rare earths. The powerful magnetic fields produced by these objects have several uses in industry. Among the types of magnets used most commonly are those made from rare earths. Two dominate this field in particular. They are the neodymium magnet and the samarium cobalt version which preceded the former into the market.
Neodymium magnets are rare-earth magnets. As such, they are composed of rare elements that are used to form alloys. As with other rare earths, magnet manufacturers use neodymium to form extremely strong permanent magnets by combining it with iron and boron in a magnetic compound. Magnets made this way have essentially replaced all other magnets in industrial use around the world.