Jigs are a large category of tools for woodworking, ironwork, fitter, machinery, electronic control and other handicrafts. In fact, "jigs" are foreign words. In mainland my country, they are mainly called fixtures. As a tool to assist in controlling position or movement (or both).

Main uses: It has been widely used before the industrial era, including mechanical fixtures, woodworking fixtures, welding fixtures, jewelry fixtures, and other fields. Certain types of jigs are also called "molds" or "auxiliary tools" and their primary purpose is to reproduce a certain part reproducibly and accurately. An obvious example is when duplicating keys, the original key is usually fixed on a jig, so that the machine can copy the new key based on the appearance of the original key. Many jigs are produced because of business needs, because many types of jigs are customized, some to increase productivity, repeat specific actions, or make work more precise. Because the design of fixtures is basically based on logic, similar fixtures may be produced separately because they are used at different times and places.

A drilling jig is a tool that can be used to guide twist drilling equipment or other drilling devices to the exact center of each hole by moving the mold and can be used on multiple interchangeable parts. To speed up the type of jig that is repeatedly positioned in the center of the hole, in ironworking practice, a typical practice is to leave a hardened bushing in each hole of the drilling jig to prevent the twist drill from cutting into the jig. Due to the widespread use of CNC machines (CNC) in the manufacturing industry, where servo controllers have the ability to automatically move the tool to the correct position, the need for drilling jigs (and the work of operators using drilling jigs) is less than before. .