Bolt: A type of fastener consisting of a head and a screw (cylinder with external threads), usually matched with a nut or screw hole, and used to connect two objects with through holes or screw holes;
Stud: A type of fastener with no head and only external threads at both ends;
Screw: It is also a type of fastener consisting of a head and a screw. It is usually divided into: machine screws, set screws, and special purpose screws;
Nut: It has an internal threaded hole and is generally flat hexagonal or cylindrical in shape. It is used with studs and bolts to connect two objects to make them a whole.
Self-tapping screws: These screws have high hardness and can be screwed directly into components.
Pins and keys: Mainly used for positioning parts, connecting parts, fixing parts, and transmitting power.
Washers: divided into: oblate ring, elastic washers