A monarchy is a form of government in which sovereignty is actually or nominally embodied in a single individual, the monarch. A monarch that has few or no legal restraints in state and political matters is referred to as an absolute monarchy, a form of autocracy. Monarchies are associated with political or sociocultural hereditary rule, in which monarchs rule for life (although some monarchs do not hold lifetime positions). Throughout history, monarchies have been abolished, either through revolutions, legislative reforms, coups d'état or wars. The twentieth century saw a major escalation of this process, with many monarchies violently overthrown by revolution or war, or abolished as part of the process of decolonization. The 21st century has already seen several monarchies abolished, usually by peaceful means in a referendum.
Monarchy was the most common form of government into the 19th century, but it is no longer prevalent, at least at the national level. Where it exists, it now often takes the form of constitutional monarchy, in which the monarch retains a unique legal and ceremonial role, but exercises limited or no political power pursuant to a constitution or tradition which allocates governing authority elsewhere. Currently, 44 sovereign nations in the world have monarchs acting as heads of state—16 of those are Commonwealth realms that recognize Queen Elizabeth II as their head of state.
Liberal democracy traces its origins, and its name, to the European 18th century, also known as the Age of Enlightenment. At the time, the vast majority of European states were monarchies, with political power held either by the monarch or the aristocracy. Near the end of the 18th century, these ideas inspired the American and French Revolutions, the latter giving birth to the ideology of liberalism, and instituting forms of government that attempted to apply the principles of the Enlightenment philosophers into practice. Reforms and revolutions helped move most European countries towards liberal democracy. Liberalism ceased being a fringe opinion and joined the political mainstream.