What are the tiny magnets inside a substance called that align when the substance is near a magnet?

The tiny magnets inside a substance that align when the substance is near a magnet are referred to as domains. In the context of magnetism, a domain is a region within a magnetic material where the magnetic moments of atoms are aligned in the same direction. When an external magnetic field is applied, these domains can rotate or align themselves with the field, which contributes to the overall magnetization of the material.

In ferromagnetic materials, such as iron, these domains can exist in various orientations and can be randomly arranged in an unmagnetized state. When exposed to a magnetic field, the majority of these domains align with the field, which enhances the material's magnetic properties. This phenomenon is key in understanding how materials become magnetized and how magnets interact with various substances.