What defines magnetism in terms of materials?

The defining characteristic of magnetism in terms of materials is their ability to attract certain materials, particularly ferromagnetic substances like iron, nickel, and cobalt. This attraction occurs because these materials have magnetic domains that can align themselves with an external magnetic field, leading to a net magnetic effect.

When a ferromagnetic material is subjected to a magnetic field, the individual magnetic dipoles within the material tend to align in the direction of the field. This alignment enhances the material's overall magnetism and enables it to exhibit magnetic properties, such as attraction to a magnet.

Other materials that do not exhibit this attraction, such as wood or plastic, are generally considered non-magnetic. Therefore, the essence of magnetism is closely linked to this ability to attract objects that have a specific magnetic response, making the ability to attract certain materials like iron the correct definition of magnetism.