Magnetism exerts influence on metals and magnetically charged bodies. Magnetism charges an object with two poles. These repel like poles and attract opposing poles. As the entire Earth itself is magnetically charged, a compass' needle will align itself with the Earth's magnetic field. Objects of magnetic materials that have not themselves been magnetically charged will be attracted to a magnet of either pole.

On the Other: Not All Objects Are Magnetic

The list of materials that can be magnetically charged, or magnetized, is quite small. Magnetism can exert a powerful effect on steel and iron, but materials such as glass, water and organic tissue cannot be magnetically charged. There is also concern that exposure to magnetic fields may lead to cellular damage, cancer and tumors.

Bottom Line

Magnetism is known to exert a powerful effect on certain materials. It is a force that permeates the entire Earth, and its use can be seen in compasses, household magnets and numerous electronic devices. Its effect is not universal, however, and the continued scientific research into magnetism's deleterious effect on human health deserves attention.

Source:

ScienceCastle.com: Magnetism

mcwdn.org: Magnetism

DoctorsLounge.com: Magnets and Health