A tap is a threaded tool that is used to cut or repair threads in the inner side of holes. This is to say that, taps create female threads that hold nuts in solid materials like metal. This process is known as tapping. A die, on the other hand, is the tool used to make threads on fresh bolts or to repair damaged male bolts or screws. This process is known as threading. These tools make it very easy to repair cars, motorcycles and boats, to name only a few. There are several types of taps and dies used for different purposes.