The following definitions are what the author means by the various terms. Your mileage may vary.
(Note that not everyone will fall neatly into one of these two categories.)
A liberal typically opposes any regulation of personal behavior, such as religion or sexuality, as long as said behavior does not infringe upon non-consenting parties. Liberals also favor people having democratic input, sometimes in the form of government regulation, into economic and social decisions that affect their lives.
Sometimes libertarians refer to themselves as the real liberals, or "classical liberals" (though their claim is debatable). Libertarians oppose any governmental authority over either personal or economic activity, as long as no "force or fraud" (narrowly defined) is involved. As I see it, the main difference between liberals and libertarians is that the latter tend to focus only on ways that the state can restrict people's freedom. Liberals believe that people are not really free to develop their full potential if it takes all their resources just to survive, if they are unfairly discriminated against, or if they do not have access to basic self-improvement tools such as quality education and employment. To the extent that the economic system allows those conditions to continue, it also restricts freedom.
Contrary to what some conservative propagandists would have you believe, liberalism is not synonymous with "big government" or the Democratic Party. Liberals do tend, however, to see democratic government as "us" and not "them".
(see also Eric Zorn on liberalism, and Rebecca Knight's The Finer Points of Liberalism)
(see also the Turn Left political glossary.)
Last modified May 28, 2002.