This is from the Wikipedia entry on Libertarianism, in the “Anti-Statist Doctrine” section.

Libertarians consider that there is an extended domain of individual freedom defined by every individual’s person and private property, and that no one, whether private citizen or government, may under any circumstances violate this boundary. Indeed, libertarians consider that no organization, including government, can have any right except those that are voluntarily delegated to it by its members — which implies that these members must have had these rights to delegate them to begin with.

Thus, according to libertarians, taxation and regulation are at best necessary evils, and where unnecessary are simply evil. Government spending and regulations should be reduced insofar as they replace voluntary private spending with involuntary public spending, and replace private morality with public coercion. To many libertarians, governments should not establish schools, run hospitals, regulate industry, commerce or agriculture, or run social welfare programs. Nor should government restrict sexual practices, gambling, drug usage, or any other ‘victimless’ crimes. Libertarians also believe in an extremely broad (and in some cases all-inclusive) interpretation of free speech which should not be restricted by government. For libertarians, government’s main imperative should be Laissez-faire — “Hands off!” — except to protect the individual rights recognized by libertarianism.

Libertarians believe in minimizing the responsibilities of citizens towards the government, which directly results in minimizing the responsibilities of the government towards its citizens.