Ruling class is a term to describe a social class that rules over another. The ruling class has historically been the rich and the educated. There has always been a ruling class of sorts, from nobles and wealthy land owners which populated fuedal societies to the monarchies of the United Kingdom.
The term ruling class, in the political sense, originated in Karl Marx's work The Communist Manifesto. In it Marx argued that the ruling class changes as the means of production alters, something he called historical materialism. Marx predicted the ruling class, the capitalist bourgeoisie, would be overthrown by the under class, the proletariat. Due to a rise in global living conditions and technological advances, Marx's vision never came to pass.