Ferromagnetic materials are substances that exhibit a strong and spontaneous magnetism with or without an external magnetic field. They are a certain group of substances that tend to manifest or display strong magnetism in the direction of the field due to the application of a magnetic field. Ferromagnetism is a unique magnetic behavior that is exhibited by certain materials such as iron, cobalt, nickel, and certain rare-earth metals. Ferromagnetic materials can be divided into magnetically soft materials like annealed iron, which can be magnetized but do not tend to stay magnetized, and magnetically hard materials, which do. Permanent magnets are made from hard ferromagnetic materials, such as alnico, and ferrimagnetic materials, such as ferrite, that are subjected to special processing in a strong magnetic field during manufacturing to align their internal microcrystalline structure, making them difficult to demagnetize.

The cause of magnetism in ferromagnetic materials is mainly due to the alignment patterns of their constituent atoms. In an unmagnetized ferromagnetic material, atomic dipoles in small regions called domains are aligned in the same direction, and the domains exhibit a net magnetic moment even in the absence of an external magnetizing field. Ferromagnetic materials have various unique properties, such as being able to be permanently magnetic or gain attractive powers and can attract each other.

Most materials that exhibit ferromagnetism are metals, such as metallic alloys and rare-earth magnets. Common examples of ferromagnetic substances are iron, cobalt, nickel, gadolinium, neodymium, and ferromagnetic ceramics.