Liberal democracy is a political ideology and a form of government in which representative democracy operates under the principles of liberalism. It is characterised by fair, free, and competitive elections between multiple distinct political parties, a separation of powers into different branches of government, the rule of law in everyday life as part of an open society, and the equal protection of human rights, civil rights, civil liberties, and political freedoms for all people. To define the system in practice, liberal democracies often draw upon a constitution, either formally written or uncodified, to delineate the powers of government and enshrine the social contract. After a period of sustained expansion throughout the 20th century, liberal democracy became the predominant political system in the world.