Republicanism is the idea in which elected leaders represent the interests of the people. Historically, it ranges from the rule of a representative minority or oligarchy to popular sovereignty. It has had different definitions and interpretations which vary significantly based on historical context and methodological approach. The word "republic" derives from the Latin noun-phrase res publica (public thing), which referred to the system of government that emerged in the 6th century BCE following the expulsion of the kings from Rome by Lucius Junius Brutus and Collatinus.