Bolts are a common fastener, similar to screws, also made of metal and have a threaded structure. The bolt is usually composed of two parts, screw and nut, and the screw is different, one end of the bolt is not threaded, but has a special head structure. The head of the bolt is usually hexagonal so that a spanner or spanner can be used to rotate the bolt. The other end of the bolt has a series of threads for fastening in conjunction with the nut. Bolts are used in a similar way to screws, requiring the bolt to be rotated so that it is tightly attached to the nut. The advantage of the bolt is that the tightening force can be adjusted by the tightness of the nut, which is more flexible. Bolts are widely used in machinery manufacturing, construction, automotive industry and other fields for connecting and fixing various parts. It should be noted that the selection of bolts should be determined according to the specific application scenarios and requirements, including the material, length and thread type of bolts. Correct selection and use of bolts can ensure safe and reliable fastening results.