Boiled peanuts have lots of salt. It's like cooking dried beans, sort of, except with a lot more salt. Boiling them makes the peanuts soft, but not the shells, you still have to shell them. It takes about 4 hours of boiling for them to be done, but some people prefer them a little undercooked, they are heathens.
It's a southern thing. Florida, and Georgia especially, but I think South Carolina likes them too. Not sure about some of the other southern states. In the summer time you can drive around and see signs that say "boiled green peanuts" those are the best. Green means they were picked within a couple days, they're not actually green. The longer they sit after they've been picked the dryer they get, they're still good, just not as good.
PEANUTS.