Normal glass is transparent and allows vision to pass through it. In certain application it is important to allow light while eliminating or obscuring the vision as in the case of a bathroom windows.
Glass has very neat, clean and glossy surface. One of the surfaces can be frosted by blasting sand or abrasives under high pressure, through a nozzle. A very thin layer of material is removed and the sand or abrasive comes a pitting on the surface obscuring its “see through” property but not obstructing the passage of light. The final glass is known as frosted.