Neodymium is the most powerful permanent magnetic material of which we are currently aware. It is also affordable, making it suitable for myriad applications. The chemical composition of a neodymium magnet is Nd₂Fe₁₄B, which is two atoms of neodymium, fourteen iron atoms, and one boron atom. A neodymium magnet is a rare-earth magnet, in contrast to conventional ferrite and ceramic magnets. Rare-earth magnets are distinct in that they contain atoms from either the lanthanide or actinide series in the periodic table.

Neodymium magnets are the greatest of the rare-earth magnets. The strength of their magnetic field at the poles ranges from just under 1 tesla (T) to as high as 1.5 T. Because they are cheap - you can get a small neodymium magnet for a single US dollar (USD) - these magnets are used quite frequently in industry and among hobbyists and dabblers. For example, every computer hard drive has a small neodymium magnet which helps direct the needle that reads data. They can also be found in high-end speakers and science classrooms around the world.

One of the only downsides to the neodymium magnet is that its magnetic field loses some intensity when temperatures are too high. This precludes their use in electronics applications in which a lot of heat is generated. There exist versions of the neodymium magnet that perform better under higher temperatures, but in these cases strength must be sacrificed.

Neodymium magnets are incredibly strong. A neodymium magnet the size of a quarter can suspend a piece of iron weighing dozens of kilograms. Two such magnets snapping together at the wrong angle can pinch your skin and draw blood. Neodymium magnets the size of a golf ball can be extremely dangerous, wiping credit cards, sending metallic objects flying, and potentially causing bodily harm if used without care.

For all their danger, neodymium magnets can be used in numerous fun and educational projects. Ferrofluid and magnetic viewing film are commonly used to view magnetic field lines in a physical medium. Carefully arranged neodymium magnets can cause diamagnetic levitation, a peculiar phenomenon that can even levitate live objects such as some frogs. If you try to drag a neodymium magnet along a non-magnetic conductive surface such as aluminum, it will engage in 'magnetic breaking' and be extremely difficult to move. Due to their awe-inspiring powers of magnetism, neodymium magnets are a toy best left to reasonably cautious adults.