Mechanical fasteners are devices used to join two or more objects together securely. Common types include bolts, nuts, screws, and washers. They are essential in various applications, from construction to automotive manufacturing, providing strength and stability to structures and machinery. These fasteners work by creating a physical connection, often through threads or friction. Proper selection and installation are crucial to ensure the integrity of the assembly. Mechanical fasteners can be easily removed and reused, making them a versatile choice for many projects.