Bolt (fastener)

A bolt is an externally helical threaded fastener that fastens objects with unthreaded holes together. This is done by applying a twisting force (torque) to a matching nut. The bolt has an external male thread requiring a matching nut with a pre-formed female thread.^[1] Unlike a screw, which holds objects together by the restricting motion parallel to the axis of the screw via the normal and frictional forces between the screw's external threads and the internal threads in the objects to be fastened, a bolt prevents that linear motion via the frictional and normal forces between the bolt's external threads and the internal threads of the matching nut (not objects to be fastened, which is what allows the bolt to secure objects with unthreaded holes), which can be tightened by applying a torque which moves the nut linearly along the axis of the bolt and compresses the objects to be fastened.