The term cladding has the following meanings:

1. Regarding optical fiber in telecommunication, cladding is one or more layers of material of lower refractive index, in intimate contact with a core material of higher refractive index. (Source: from Federal Standard 1037C and from MIL-STD-188)
2. A process of covering one metal with another (usually achieved by pressure rolling, extruding, drawing, or swaging) until a bond is achieved.
3. In building construction, "cladding" may refer to the application of one material over another to provide a weather-proof layer intended to control the infiltration of weather elements. Cladding does not necessarily have to provide a water-proof condition but is instead a control element. This control element may only serve to safely direct water or wind in order to control run-off and prevent infiltration into the building structure. Cladding applied to windows is often referred to as window capping and is a very specialized field. A number of excellent pictures illustrating window cladding can be found at http://www.windowcapping.com and many terms are also explained.