A hex head screw is a fastener with a hexagonal-shaped head and is used to attach materials together. There are many different terms used to describe this type of screw, such as hex bolt, hex cap screw, hex machine screw, or simply hex head. These terms may be used interchangeably, but there are some key differences between them. A hex bolt typically has a larger diameter and is designed to be used with a nut, while a hex cap screw is threaded to the head and does not require a nut. A hex machine screw is generally smaller and used in more delicate applications. Regardless of the term used, all hex head screws are designed to provide a secure and reliable attachment for a variety of projects.