There are a lot of nuts out there. There are walnuts, chestnuts, pecans, Brazil nuts, cashews, pistachios, and many others. And then there's the cheap, easy-to-open, grown-in-the-dirt peanut. It is very popular, but it's not a nut. It's a legume, part of the pea family.
Peanuts are very common. Unlike nuts that grow on trees, peanuts grow underground. Peanut farms grow them by the truckload, making peanuts fairly inexpensive. Although they are not nuts, most people think of them as nuts.
Some peanuts are dry roasted. Some peanuts are boiled. Still other peanuts are ground up to make - you guessed it - peanut butter. Some cooking oils are even made from peanuts. There are lots of uses for peanuts.