Nut Bolt Washer.
This bolt has a clear shank under the head. It should be used in combination with the nut and washer. Screw the nut and the bolt and it can be used for fastening materials.
The nut is the fastener with a threaded hole and used in combination with the bolt. Both have a hexagonal shape, 6 sides or faces, so it can be easily used with tools, like a wrench, for tightening.
A washer is the thin ring lying next to the bolt. Normally it should be used to distribute the force of the nut. Washers can also be used if you need to prevent corrosion when using different materials like steel and aluminium.