Bolts are mechanical elements for tightening and fixing parts to parts. It consists of a male-threaded shaft and head, and it is used by tightening it with a mechanical element called a “Nut” or by tightening it into a female-threaded hole.A thread that is threaded on the entire shaft is called a full thread, and a thread that is threaded by a specific length from the tip is called a half thread and some have holes for safety wires on the head and holes for cotter pins on the threads.Bolts are made by various materials such as alloys and resins such as steel, stainless steel, aluminum alloys, and titanium alloys. There are also many types of shapes and head shapes depending on the application. So it is wise to check which kind of bolt to use that fit the most in your work.