A stud is a type of fastener that can be classified into 3 types:

1. Full Thread Stud that has continuous threads that run the full length of the part. Diameter, thread pitch, total length, material grade and finish need to be specified at time of order.
2. Double End Stud is a part that has an unthreaded body with threads on both ends of the total length.  Diameter, thread pitch and thread length for each end, total length, material grade and finish need to be specified at time of order.  Full body diameter or pitch diameter body need also to be specified. Bay Standard is a roll threader whose standard parts are produced from pitch diameter bars.
3. Single End Stud is a part that has threads on one end of the part. Diameter, thread pitch and thread length for one end, total length, material grade and finish need to be specified at time of order.  Full body diameter or pitch diameter body need also to be specified. Bay Standard is a roll threader whose standard parts are produced from pitch diameter bars.

Studs are commonly used in construction and manufacturing industries for joining two objects together, such as connecting wood or steel members or securing machinery parts. The stud typically passes through the parts needing to be joined and secured with nuts on one or both ends. Threaded studs come in a variety of sizes and materials.