A screw is a common fastener, usually made of metal, with a threaded structure. It is usually composed of two parts: screw and nut. The screw has a series of threads, and the nut has a corresponding threaded hole, both by rotating the screw to achieve the function of tightening. There are many different types of screws, including differences in thread shape, head shape, material, and so on. Common screw types include threaded screws, self-tapping screws, mechanical screws, etc. Screws are widely used in various fields, such as furniture manufacturing, construction, machinery manufacturing, automotive industry and so on. The use of screws is relatively simple, usually requiring the use of a spanner or screwdriver to rotate the screw so that it is tightly connected to the nut. The fastening force of the screw can be adjusted by the force of rotation to meet different needs.