Oligarchy (from Greek ὀλιγαρχία (oligarkhía); from ὀλίγος (olígos), meaning "few", and ἄρχω (arkho), meaning "to rule or to command")[1][2][3] is a form of power structure in which power effectively rests with a small number of people. These people could be distinguished by royalty, wealth, family ties, education, corporate, or military control. Such states are often controlled by a few prominent families who pass their influence from one generation to the next.[citation needed] In his 2011 book Oligarchy, Jeffrey A. Winters defines oligarchy as "the politics of wealth defense by materially endowed actors". In Winters' definition, massive wealth is the key factor in identifying oligarchs.
Throughout history, oligarchies have been tyrannical (relying on public obedience and/or oppression to exist) or relatively benign. Aristotle pioneered the use of the term as a synonym for rule by the rich,[4] for which the exact term is plutocracy, but oligarchy is not always a rule by wealth, as oligarchs can simply be a privileged group, and do not have to be connected by bloodlines as in a monarchy.