Liberalism may be used to describe any ideology not bound by orthodox tenets or established forms in political or religious philosophy, in contrast to conservatism.
2. An alternate usage denotes a particular class of sociopolitical ideologies.
Liberalism is rooted in the Enlightenment, the central developer of which is seventeenth century English political philosopher John Locke. Liberalism is the view that the autonomy and dignity of the individual should be protected and not infringed by the state. Consequently, liberalism holds, we have certain civil and political liberties and rights that it is the duty of the government to uphold, and government derives its authority to govern by law by the consent of the governed. In Locke's day, liberalism was contrasted with monarchism, mercantilism, and various kind of religious fundamentalism; since then, it has developed in many ways and been contrasted with many different other political theories, especially socialism and various forms of collectivism.
John Locke, Thomas Hobbes, Jean-Jacques Rousseau, and Immanuel Kant developed the concept of the "social contract", though the writings of Hobbes and Rousseau include many illiberalisms. Also John Stuart Mill, nationalism.
Early liberals believed in individual rights and limited government. This is now, in the United States anyway, called "libertarianism." The word "liberal" still has this meaning in Europe, but not in the United States, where it more closely describes the ideology known as "new liberalism" or an alternative purely political doctrine known as political liberalism.
At present in the U.K. and Europe, Liberalism is a political current which regards freedom as the most important thing and as such rejects large government influences. Ethically, liberals prefer to have the person decide his or her ethics himself or herself, without government influence. Government should only forbid behaviours that have a substantial negative impact on others. Economically, liberals are in favor of a Free Market Economy, again with as little influence from government as possible. In their opinion, everyone doing what (s)he thinks is best, is the best way to ensure that the total outcome is best for all. The opponents of liberals are Conservatives in the ethical range and Socialists in the economical.
In the United States, starting with the increase in size of government with the Great Depression during the 1930s, liberals advocated government programs as a solution to many economic and societal problems.
In Europe, liberalism usually means minarchism; while in the U.S., it refers to new liberalism. The usage in countries in other parts of the world varies; some use it in the European sense, others in the U.S. sense.
In the UK liberalism is generally connected with the history of the Liberal Democrats and the "moderation" sense of the word liberal. Attempts to use this term in the UK in the American sense by the right as a derisory term for people they don't like has caused a fair degree of confusion. See Looking for an Enemy.
Minarchists also lay claim to the term "classical liberalism".
Some separate liberalism into political liberalism and economic liberalism, so as to be able to agree with one and disagree with the other. Minarchists reject such a division, because they believe liberalism to be neither an economic nor a political doctrine, but rather a theory of law.