Nuts are a type of fastener that are used to secure a bolt or screw in place. Nuts have a threaded hole that matches the thread of the bolt or screw, and they are usually tightened by turning them clockwise with a wrench or a socket. Nuts come in different shapes, sizes, materials and grades, depending on the application and the load they need to withstand. Some common types of nuts are hex nuts, wing nuts, lock nuts, flange nuts and cap nuts. Nuts can also have various features, such as washers, inserts, slots or holes, to improve their performance or ease of use.