Nut (fruit) usage of the term is less restrictive, and many nuts (in the culinary sense), such as almonds, pecans, pistachios, walnuts, and Brazil nuts, are not nuts in a botanical sense. Common usage of the term often refers to any hard-walled, edible kernel as a nut. A nut in botany is a simple dry fruit in which the ovary wall becomes increasingly hard as it matures, and where the seed remains unattached or free within the ovary wall. Most nuts come from the pistils with "inferior" ovaries (see flower) and all are "indehiscent" (not opening at maturity). True nuts are produced,
Plate nut These nuts are made up of variety of soft and hard materials. The choice of material depends on environment to which nut is subjected. Soft materials like copper or brass are used when nut is used in electrical application. Hard materials are used when nut is subjected to high stress environment. Sometimes stainless steel or nickel-plated nuts are used in order to increase corrosion resistance. Locknut types are available, which utilize deformed threads or a nylon locking element, much like a nyloc nut. These locking plate nuts are used when the nut is subjected to constant changes in environment or