Rare-earth magnets are strong permanent magnets made from alloys of rare-earth elements. Developed in the 1970s and 1980s, rare-earth magnets are the strongest type of permanent magnets made, producing significantly stronger magnetic fields than other types such as ferrite or alnico magnets. The magnetic field typically produced by rare-earth magnets can exceed 1.4 teslas, whereas ferrite or ceramic magnets typically exhibit fields of 0.5 to 1 tesla.  There are two types: neodymium magnets and samarium–cobalt magnets. Magnetostrictive rare-earth magnets such as Terfenol-D also have applications, e.g. in loudspeakers. Rare-earth magnets are extremely brittle and also vulnerable to corrosion, so they are usually plated or coated to protect them from breaking, chipping, or crumbling into powder.

Neodymium magnets, invented in the 1980s, are the strongest and most affordable type of rare-earth magnet.  They are made of an alloy of neodymium, iron, and boron (Nd2Fe14B), sometimes abbreviated as NIB.   Neodymium magnets are used in numerous applications requiring strong, compact permanent magnets, such as electric motors for cordless tools, hard disk drives, magnetic holddowns, and jewelry clasps. They have the highest magnetic field strength and have a higher coercivity (which makes them magnetically stable), but they have a lower Curie temperature and are more vulnerable to oxidation than samarium–cobalt magnets.  Corrosion can cause unprotected magnets to spall off a surface layer or to crumble into a powder.  Use of protective surface treatments such as gold, nickel, zinc, and tin plating and epoxy-resin coating can provide corrosion protection.