Cashew nuts belong to the same family as the mango and pistachio nut (Anacardiaceae). They are actually seeds that adhere to the bottom of the cashew apple, the fruit of the cashew tree (Anacardium occidentale). Cashew apples are regarded as delicacies in Brazil and the Caribbean.
Cashew nuts in the shell are not available in stores since the interior of their shells contains a caustic resin known as cashew balm. This resin, which is toxic, must be removed before they are fit for consumption. Cashew balm is used in varnishes and insecticides.