Taps and dies are cutting tools used to create screw threads, which is called threading. A tap is used to cut the female portion of the mating pair, like a nut. A die is used to cut the male portion of the mating pair such as a screw. The process of cutting threads using a tap is called tapping, whereas the process using a die is called threading. Both tools can be used to clean up a thread, which is called chasing. Tap and die sets are perfect for helping fix broken screws, nuts, bad threading, and all of those clumsy mistakes we all make.