Peanuts are not true nuts; rather, they are a member of a family of legumes related to peas, lentils, chickpeas and other beans.
Peanuts start growing as a flower, but, because of their heavy weight after pollination, they bend toward and eventually go underground where the peanut matures. Although peanuts come in many varieties, there are four main types with specific size, taste and nutrient make-up; they include Runner, Virginia, Spanish and Valencia.
Runners have become extremely popular because of their high yield. More than half of these peanuts are used for peanut butter.
Virginias have the largest kernels and are typically the peanuts you find roasted in the shell or in snack bags.
Spanish peanuts have smaller kernels and higher oil content than other types of peanuts and are covered with a reddish-brown skin. They are used mostly in peanut candies, some snack nuts and peanut butter.
Valencias are very sweet, have three or more small kernels to a pod and are covered in a bright-red skin. They are usually roasted or boiled and sold in the shell.