Amorality is the quality of existence in which the concept of morality (or right and wrong) is invalid. For a relatively simple and intuitive example of amorality: A rock which falls on a person is amoral. It is neither right nor wrong, and one cannot reasonably praise or blame the rock. "Amoralism" may also refer to the belief that the concepts of moral right and wrong do not have meaning, or to the absence of a belief in the absolute existence of any moral law, particularly with reference to human life.
Amorality is distinct from immorality, although in common use the terms "amoral" and "immoral" are often conflated. An amoral person denies the existence of morality, whereas an immoral person believes in the existence of morality but chooses not to recognize it as binding or intentionally defies it. An immoral person who violates a certain moral code may still believe in the underlying truth of that moral code.
Amoral persons either do not possess ethical concepts at all as a result of upbringing (e.g. antisocial personality disorder) or else do not subscribe to any moral code. This latter may in turn mean strong individualistic leanings that do not get codified into a universally applicable system. Someone may maintain that he will do as he likes and let others do the same, if they so desire, without turning this into a general principle as, for example, Immanuel Kant's categorical imperative would require. Making this pronouncement expresses the personal preference of the speaker, or informs about the way he is going to act, and is thus consistent. An amoralist might also make a stronger point that moral systems are arbitrary and unfounded on the whole, which is an epistemic or anthropological claim and not an ethical one. Such principled amoralism is arguably present in the philosophy of Max Stirner, philosophy of Friedrich Nietzsche, Thomas Hobbes, Daniel Quinn, Richard Garner, and to a degree the Marquis de Sade.
Immoral behavior, on the other hand, consciously or even actively violates a code of morality, rather than being irrelevant to morality. A thief may not deny that stealing is immoral, but may attempt to deflect the blame or offer excuses in order to justify his actions. Essentially, immoral individuals believe that certain things are wrong, but disregard this information, possibly resulting in feelings of guilt.