The Libertarian Party was founded in 1971, and for many years enjoyed being known as the largest third party in American. However, the Constitution Party now holds that title. Still, it has over 200,000 members nationwide, and it's 2008 candidate Bob Barr received a moderate amount of votes, and received larger amounts than both the Green and Constitution Parties.
They have achieved ballot access in 50 states three times since the parties creation, however, they have not received it in the past three elections.
Many people associate the belief system of the Libertarian party with the Laissze-Faire type of Government. Libertarians often believe in the legalization of Gay Marriage, civil liberties, and economic freedom.
In a way they are both Liberals and Conservatives, with far liberal views on personal freedom and Conservative when it comes to economic practices.