Oligarchy is a society or social system ruled by a few people. The word oligarchy is from the Greek words for "few" (oligos) and "rule" (arkhe). As societies or organizations become large it is thought that political power becomes concentrated in the hand of a few individuals. Oligarchy means "the rule of the few" and monarchy means "the rule of the one". In Oligarchy power rests with a small elite segment of society distinguished by royalty, wealth, family, military influence or occult spiritual hegemony. City-states from Ancient Greece were oligarchies.
Oligarchies are tyrannical as they are completely reliant on public servitude to exist. States controlled by politically powerful families whose children are heavily conditioned and mentored to be heirs of the power of the oligarchy. Jeffrey A. Winters defined oligarchy as "the politics of wealth defense by materially endowed actors" and Aristotle used the term as a synonym for rule by the wealthy, but oligarchy is not always a rule by wealthy people, for which the term is plutocracy as oligarchs can simply be a privileged group.
Oligarchies can bring about change forcing monarchs or dictators to share power. Such power-sharing from one person to a larger group of persons happened when English nobles got together in 1215 to force King John of England to sign the Magna Carta, a recognition of failure of oligarchy. Magna Carta was revised many times (1216, 1217, and 1225), guaranteeing greater rights to greater numbers of people, thus setting the stage for English constitutional monarchy.
Oligarchy can also be compared with Aristocracy. In an aristocracy, a small group of wealthy or socially prominent citizens control the government. Members of this high social class claim to be, or are considered by others to be, superior to the other people because of family ties, social rank, wealth, or religious affiliation. The word "aristocracy" comes from the Greek term meaning rule by the best.
Any political system eventually evolves into an oligarchy. This theory is called the Iron Law Of Oligarchy. Modern democracies should be considered as elected oligarchies. In oligarchic systems, actual differences between viable political rivals are small, the oligarchic elite impose strict limits on what constitutes an 'acceptable' and 'respectable' political position, and politicians' careers depend heavily on unelected economic and media elite.