Threading is the process of adding a screw thread onto the end of bar so that a nut or etc. can be secured to the bar or that the bar can be secured to another object. Threading can be for any length of a bar from just the tip to the entire length of the bar.
Threading has two primary forms, male and female threads. A male thread is an external thread made on the longer object to which a nut or bolt may be added e.g. a bar of circular steel. A female thread is inverse of this i.e. a thread added to the internal section of an object such as the inside of a nut which will be screwed onto a male threaded bar.
Male threads are made by securing the bar in place, and then feeding it through a rotating cutting wheel or die. As the bar passes through, chips are scratched away from the material which provides the consistent depth of the indentation required to form the thread.
Galvanizing screw threads can cause problems if the process is not done correctly.