In a threaded assembly the contact between the male and female threads takes place on the :

Pitch

The distance from a given point on one thread to a corresponding point on the next thread is called Pitch

Minor diameter

Root diameter of a thread is another name for minor diameter

Shoulder bolt

A bolt that is used to create a pivot point is called Shoulder bolt

Hangar bolt

A bolt that has wood thread on one end and machine thread on the other end is called Hangar bolt