Screw is a more general term. Anything with an external thread can be called a "screw". The exact term should be bolts, screws, and screw caps (nuts). It is a mechanical part used to fasten the connection. Standard fasteners mainly include bolts, studs, screws, set screws, nuts, washers and rivets. Standard fasteners are divided into twelve categories, and the selection is determined according to the use occasion of the fastener and its use function.