The surface of solids had long been considered simply the external boundary which determined the outside appearance of the solids but had no intrinsic character of its own. The concept that surfaces have specific properties and are the first and foremost means of communication between individual things and the rest of the universe is fairly new, coming into prominence only in the early sixties. This new concept of surface properties was the result of a vast accumulation of knowledge due to recent development of research in this area. This breakthrough of surface science resulted from the...