To summarize, here are the main branches of the Objectivist philosophy, in a nutshell.
1. Metaphysics: Objective reality. Things are what they are, no matter what anyone thinks, wishes, or desires.
2. Epistemology: Reason. One can only grasp reality by using the rational faculty of reason.
*The above lead to a particular view of human nature--man is a rational being whose basic choice is to think or not to think--which leads into the 3rd branch of philosophy*
3. Ethics: Selfishness. Pursue your own self-interest, your own happiness. Your life is yours.
4. Politics: Capitalism. The freedom to act, to trade, to deal with whomever you choose, with the government intervening only in response to physical force or fraud.