What component is used to prevent damage to materials by distributing the load of a bolt head?

A washer is specifically designed to distribute the load of a bolt head or nut over a larger surface area. This helps to prevent damage to the material being fastened and ensures that the joint maintains its integrity under stress. By spreading out the force exerted by the bolt head, the washer minimizes the risk of crushing or deforming the underlying surface, which can occur if the bolt head is placed directly against the material.

In various applications, washers also serve to reduce friction between surfaces, help lock the components in place, and provide a seal in some cases. The other components listed, while useful in fastening assemblies, do not primarily serve the purpose of load distribution in the same way that washers do.