This document discusses different types of jigs and their applications. It begins by defining jigs as production tools used to manufacture duplicate parts accurately. The main types of jigs discussed are drilling jigs, which are used to machine holes. Different types of drilling jigs are described, including template jigs, plate jigs, box jigs, sandwich jigs, diameter jigs, angular jigs, pot jigs, turnover jigs, multi-station jigs, standard jigs, universal jigs, and solid jigs. Jigs are used to reduce costs, increase productivity and accuracy, and enable mass production of interchangeable parts.