A bolt is a type of fastener used to hold objects together. It typically consists of a cylindrical shaft with a head on one end and a threaded portion on the other. Bolts are often used in construction and machinery to secure parts, providing strength and stability to structures. Bolts are usually paired with a nut, which is a hexagonal piece that fits onto the threaded end of the bolt. When tightened, the nut compresses the materials being joined, creating a strong connection. Common materials for bolts include steel, stainless steel, and aluminum, each chosen for specific applications based on strength and corrosion resistance.