Ayn Rand presents a distinct philosophy named Objectivism that unites ethics, epistemology and metaphysics into one world view. She argues that each individual should look after their own interests and that sacrafcing yourself for others in anti-life because it is anti-survival and irrational. She sees the ideal society as one based on natural rights and therefore has a government that protects these rights and does not interefere with capitalism, the only economic system that recognises natural rights. As she sees it, the United States was founded on the supremancy of the rights of man and the subjugation of government to protect those rights. The government must have a monopoly on the use of force because it's job is to protect the people. It must enforce laws and defend the country from attack. It has no right to compel a man to act against his wishes. For example, the government has no right to tax an individual to support some goal such as building a bridge. The government has no right to viloate a person's rights for the public good. The most basic right is the right to life which means the right to act as one deems necessary to support that life. Since a man cannot support his life without property, the necessary corralary to the right to life is the right to property. The government, therefore, never has the right to take your property.
Rand rejects a number of philosophies as being mystic which she defines as being based on something other than reason, i.e. faith or emotion. Reason is what allowed man to survive and shape the world to his needs and an abandonment of reason is an abandonment of life. The philosophy she despises most if that of Immanuel Kant and his "Categorical Imperative". This she calls the doctrine of altruism, of self sacrifice, of giving up your interests for the interests of the group. She calls attention to the fact that the worst tyrannies in history including Nazi Germany and Soviet Russia were based on altruistic doctrines.
Ayn Rand wrote philisophical essays and fictional works that present her views throught the story. Atlas Shrugged is a fictional story that encompasses the Objectivist philosophy. Fountainhead captures a number of elements of this philosophy as does Anthem and We the Living. Non fiction books that present her philosophy well include "The Virtue of Selfishness" and "Capitalism: The Unknown Ideal". For a complete coverage of her philosophy read "Objecitvism: The Philosophy of Ayn Rand" by Leonard Peikoff.