Politics of Sri Lanka takes place in a framework of a presidential representative democratic republic, whereby the President of Sri Lanka is both head of state and head of government, and of a  multi-party system. Executive power is exercised by the government. Legislative power is vested in both the government and parliament. For decades, the party system has been dominated by the socialist Sri Lanka Freedom Party and the conservative United National Party. The Judiciary is independent of the executive and the legislature. The Politics of Sri Lanka reflect the historical and political differences between the three main ethnic groups, the majority Sinhala and the minorities Tamils and Muslims, who are concentrated in the north and east of the island.