Gaetano Mosca's term for the organised minority that, in every society beyond the most primitive, actually exercises political power over the unorganised majority.
In more detail
Mosca argued that minorities rule because they are organised and justify their rule through a 'political formula' such as divine right or popular sovereignty. Regimes differ in how their political class is recruited and renewed and in whether power is balanced by distinct social forces. The term is now used loosely for professional politicians as a group; critics of elite theory argue that it says little about how responsive elites are to voters.