Why are rare earth magnets so much more powerful than other magnets?

[Tregg Smith]

Can someone explain why a rare Earth magnet is so much more powerful than the lesser magnet? And why is it called rare earth? Thank you

 

[Andy Resnick]

I'm not sure the reason why certain compounds have such high coercivities, but they are called 'rare earth' because the elements (Nd, Sm, Pr, etc) are in the Lanthanide series.