Diamagnetic materials are substances that are not attracted to magnetic fields. Instead, they create a weak magnetic field in the opposite direction when exposed to an external magnetic field. This means that when a diamagnetic material, like bismuth or copper, is placed in a magnetic field, it will slightly repel the field, making it very weakly magnetic. One interesting property of diamagnetic materials is that they can be levitated in strong magnetic fields. For example, small frogs have been levitated using powerful magnets due to their diamagnetic properties. This fascinating phenomenon showcases the unique behavior of these materials in the presence of magnetism.