Republicanism is a philosophy derived from a belief in the old Republics of Rome and the philosphy of the Enlightenment. The Republic revolves around the idea of a free body politic. The implications of a free republic is the idea of participatory and active citizens. The original republics and those dating from the 11/12th cenutry Renasiance Italy e.g. Florence and Venice were small, self-governing cities/communities. The Republic was in essence a type of indirect democracy, where citizens elect representatives instead of governing themselves. The key theorists on republican democracy were Machiavelli (in The Discourses) and Locke (in the Two Treatises of Goverment).
In modern times Republicanism has been simplified, so that Republican holds the belief that the best form of government is a republic as opposed to a monarchy. Unlike proponents of democracy, socialism, or communism, modern republicans rarely argue on the basis of universal principles that a republic is the best form of government in all nations. Rather republicanism is generally a local political movement that argues for the abolition of the monarchy in a particular nation. Because most monarchs in constitutional monarchies have limited power, arguments over republicanism in the late 20th and early 21st century are more often about symbolism than about actual transfers of power.
The term republic most commonly means the system of government in which the head of state is elected for a limited term, as opposed to a constitutional monarchy. Republicanism in this sense is support for the abolition of constitutional monarchies. This definition is particularly appropriate in countries such as Australia, where the abolition of the monarchy is a major political issue, and other Commonwealth nations such as Canada, New Zealand, Jamaica and Barbados. In these countries, republicanism is largely about the post-colonial evolution of their relationships with the United Kingdom. Even in the United Kingdom, where there has never been much popular support for republicanism, it nonetheless commands a significant minority position. There, however, it's motivated more by the decreased popularity of the Royal Family as well as the classical argument against monarchy versus the egalitarian aspects of republicanism.
Republican movements have been successful in France, Italy, Greece, Ireland, Ethiopia, China and Russia. In the case of Italy and Greece, the abolition of the monarchy was intended because the monarchy had become discredited for cooperations with Mussolini in the former case, and the Greek generals in the latter.
In the case of Russia and Ethiopia, the overthrow of the monarchy was in the context of a general Marxist revolution.
Spain has been a rare example in which a monarchy has been restored in the 20th century.
Republicanism in the United States
According to the older definition of the term, the United States of America is a republic, not a democracy. (Although most people, including most Americans, call it a democracy, they are using the modern definition, not the older one referred to here). This usage of the term republic was particularly common around the time of the American Founding Fathers. In contrast to the "Confederation" under the Articles of Confederation, the authors of the U.S. Constitution intentionally chose what they called a republic for several reasons. For one, it is impractical to collect votes from every citizen on every political issue. In theory, representatives would be more well-informed and less emotional than the general populace. Furthermore, a republic can be contrived to protect against the "tyranny of the majority." The Federalist Papers outline the idea that pure democracy is actually quite dangerous, because it allows a majority to infringe upon the rights of a minority. By forming what they called a Republic, in which representatives are chosen in many different ways (the President, House of Representatives, Senate, and state officials are all elected differently), it is more difficult for a majority to control enough of the government to infringe upon a minority. (On an unrelated note, Republicanism can also mean the doctrines of the Republican Party).