Individualism is the belief that the interests of the individual should take precedence over the interests of the state or social group.
Closely associated with some variants of the ideal of capitalism, libertarianism and classical liberalism this belief relies on the notion that individuals know best and that society has the right to interfere in the person’s decision making process only when a very compelling need to do so arises (and maybe not even those circumstances).
Some founders of the US constitution (the Jeffersonian Democratic-Republicans) believed that the government should enumerate these rights in the constitution it self; this idea later lead to the Bill of Rights, which was a strong stand for the individual in society.
Opposing individualism are the ideals of Marxism, socialism, communism, (strong) nationalism, Stalinism, Maoism, Nazism, monarchy and collectivism.
This needs serious revision; please edit. Yes. For one thing, individualism isn't only a political doctrine.