What is a Libertarian?

A favorite of mine:

How much liberty is good for the individual?
How much government do we need?

The libertarian, or "classical liberal" perspective is that individual well-being, prosperity, and social harmony are fostered by "as much liberty as possible" and "as little government as necessary."

These are open-ended answers that leave a lot to explore: What's possible? What's necessary? What are the practical implications? The unsolved problems?
According to Funk and Wagnall's Dictionary

lib-er-tar-i-an, n. 1. a person who advocates liberty, esp. with regard to thought or conduct.... advocating liberty or conforming to principles of liberty.

According to American Heritage® Dictionary of the English Language: Fourth Edition. 2000.

NOUN: 1. One who advocates maximizing individual rights and minimizing the role of the state.

The Challenge of Democracy (6th edition), by Kenneth Janda, Jeffrey Berry, and Jerry Goldman

Liberals favor government action to promote equality, whereas conservatives favor government action to promote order. Libertarians favor freedom and oppose government action to promote either equality or order.

According to Microsoft® Encarta® Online Encyclopedia 2000 © 1997-2000 Microsoft Corporation

Libertarianism, political philosophy emphasizing the rights of the individual. The doctrine of libertarianism stresses the right to self-ownership and, by extension, the right to private ownership of material resources and property. Advocates oppose any form of taxation and favor a laissez-faire economic system.

According to David Boaz, Libertarianism: A Primer, Free Press, 1997

Libertarianism is the view that each person has the right to live his life in any way he chooses so long as he respects the equal rights of others. Libertarians defend each person's right to life, liberty, and property-rights that people have naturally, before governments are created. In the libertarian view, all human relationships should be voluntary; the only actions that should be forbidden by law are those that involve the initiation of force against those who have not themselves used force-actions like murder, rape, robbery, kidnapping, and fraud.