Opening in the surface of an object

A hole is an opening in or through a particular medium, usually a solid body. Holes occur through natural and artificial processes, and may be useful for various purposes, or may represent a problem needing to be addressed in many fields of engineering. Depending on the material and the placement, a hole may be an indentation in a surface, or may pass completely through that surface. In engineering, a hole may be blind or through if it is partial or complete depth.