Bolts are fasteners used to hold objects together, typically made of metal. They consist of a cylindrical shaft with a head on one end and threads on the other. The threaded end is designed to fit into a corresponding nut or to be screwed into a pre-tapped hole, providing a strong connection between materials. Bolts come in various sizes and types, including hex bolts, carriage bolts, and lag bolts, each serving different purposes. They are commonly used in construction, machinery, and automotive applications, making them essential components in many everyday items and structures.