A screw thread, often shortened to thread, is a helical structure. It is a ridge wrapped around a cylinder or cone in the form of a helix, with the former being called a straight thread and the latter called a tapered thread.
Nuts, bolts, and screws all have screw threads
The tightening of a nut to a bolt is like driving a wedge into a gap until it sticks through friction and plastic deformation (how the surfaces of the two objects slightly squash together).
A screw thread is one of the six simple machines which give mechanical advantage.
The mechanical advantage of a screw thread depends on its lead, which is the linear distance the screw travels in one turn or revolution.
Two screw threads with the same pitch and diameter, but a different lead