Threading is a machining technique that involves cutting or forming threads on an item's exterior or internal surface so that it can be mated with a fastener or another part. External threads are created and repaired using dies and external threading tools. Internal threads are created and repaired with taps. Threading sets may feature a variety of several types of threading and holemaking tools that can be used together for machining tasks that need many processes, or they contain multiple sizes of taps or dies.