Nuts are normally used with bolt. Hexagon nuts are the most popular type in this fastener family. Hexagon nuts with product grade C are intended for the use on the machine and facility with rough surface and does not require high precision. Hexagon nuts with product grade A and B are intended for the use on the machine and facility with smooth surface and does require high precision. Hexagon thin nuts are also called Hexagon jam nuts. They are often used when there is spacial limitation on the mating parts. They are also used in combination with Hexagon nuts for the purpose of locking.
Prevailing torque type hexagon nuts are also called hexagon locknuts. They are the nuts with nonmetallic elements (normally Nylon insert) full collars or rings at the top. They are designed to increase their break-loose torque.
A wing nut is a nut with wings. It is designed to be tighten and loosen manually without tools and drivers.