The common denominator of liberalism is the core liberal philosophy of universal individual rights & liberties, consent of the governed (governments exist for the people who have a right to change & replace them, & authority is legitimate only when it protects those liberties), political & legal equality. US modern liberalism primarily refers to social liberalism & progressivism. Liberalism elsewhere often refers to classical liberalism which more closely corresponds to US libertarianism.
American versus European usage of liberalism
Colloquially, liberalism is used differently, in its primary use in different countries. In the United States the general term liberalism almost always refers to modern liberalism. There are some parties in Europe which nominally appeal to social liberalism, with the Beveridge Group faction within the Liberal Democrats, the Danish Social Liberal Party, the Democratic Movement, and the Italian Republican Party. One of the greatest contrasts is between the usage in the United States and usage in Europe and Latin America. According to Arthur M. Schlesinger Jr. (writing in 1956), "[l]iberalism in the American usage has little in common with the word as used in the politics of any European country, save possibly Britain." In Europe, liberalism usually means what is sometimes called classical liberalism, a commitment to limited government, laissez-faire economics. This classical liberalism sometimes more closely corresponds to the American definition of libertarianism, although some distinguish between classical liberalism and libertarianism.
What constitutes a liberal party is highly debatable. In the list below, it is defined as a political party that adheres to the basic principles of political liberalism. This is a broad political current, including left-wing, centrist and right-wing elements. All liberal parties emphasise individual rights, but they differ in their opinion on an active role for the state. This list includes parties of different character, ranging from classical liberalism to social liberalism, conservative liberalism to national liberalism.
Several conservative and/or Christian-democratic parties, such as the British Conservative Party, Germany's Christian Democratic Union and Spain's People's Party, are also considered to be neoliberal leaning or have strong liberal conservative and/or classical liberal factions, whereas some conservative parties, such as Poland's Law and Justice and Hungary's Fidesz, favour more state intervention but also support free-market solutions. Conversely, some social-democratic parties, such as the British Labour Party and the Italian Democratic Party, include liberal elements. Social liberalism and social conservatism are not mutually exclusive, and some parties espouse socially liberal economic policies, while maintaining more socially conservative or traditionalist views on society: examples of this include Finland's Centre Party (see also Nordic agrarian parties) and Ireland's Fianna Fáil, both members of the Alliance of Liberals and Democrats for Europe Party (ALDE Party). In the United States, the two major political forces, the Republican Party and the Democratic Party, are to some extent, liberal (see Liberalism in the United States and Modern liberalism in the United States).
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Not all the parties using the "Liberal" or "Freedom" labels are actually liberal. Moreover, some parties, such as the Freedom Party of Austria, were originally liberal, but have since tilted toward a populist direction and abandoned most of the tenets of liberalism. Finally, some parties, such as the United States Republican Party, Australia's Liberal Party or Norway's Progress Party are liberal mainly from an economic point of view rather than a social point of view (see economic liberalism, libertarianism and right-libertarianism).