Surface texture, also referred to as surface roughness, is an important parameter for many manufactured items.  It can be measured on ground or machined surfaces and is especially significant for polished surfaces.   The performance of optical elements and the processing from shaping, to grinding, to final polishing is largely influenced by surface roughness.  The surface roughness at each step of fabrication is a result of the operation, the substrate properties, and the conditions of the machine to part interactions, with a little chemistry thrown in for good measure