Intrinsic good refers to the ethical concept of something that is good in and of itself, simply because it is. This is contrasted with instrumental or inherent good, which are good for something. The nature and very existence of truly intrinsic good has been subject to much debate, but in the end most people accept that there is intrinsic good because morality would be entirely arbitrary and immaterial without it.  Though there are many theories on what is intrinsic good, there are basically two options: the Consequentialist and Deontological views.
 in Consequentialism
Consequentialism, the philosophical view that moral judgements are to be made based on consequences of actions, generally holds a hedonistic and eudaemonistic view of intrinsic good, that is, pleasure (simple happiness) and eudaemonia (human flourishing) are considered good. Hedonism is logical because all humans naturally want pleasure and eudaemonia, and, according to hedonists, human being fundamentally live for them alone. Consequentialists hope to achieve hedonistic ideals by promoting actions with consequences that maximize pleasure, eudaemonia, or both. This approach is a key concept of Secular humanism.  Hedonism and eudaemonism are often criticized because they are difficult to measure.
 in Deontology
Deontology is the view that actions are to be judge based on adherence to moral rules such as God's word and the categorical imperative. Deontologists typically value one's duty to the rules as the only intrinsic good. This view is popular because, like all of deontology, it is simple and easy to follow: do what we say, and you're doing it right. Duty can lead to some very strange decisions, but in the case of a more democratic alternative such as Social contract can be effective. It is also criticized because it is unclear exactly what makes the rules themselves right without resorting to hedonism.
 in Objectivism
Objectivists are unique in their rejection of objective intrinsic good, although they claim not to reject but support objective right or wrong. Instead, they claim that good is relative to the furthering of one's life alone, and that nothing is good itself, but must be good to someone for something. This position is criticized for its lack of scientific objectivity and its moral justification of just about everything, if it serves a person's self-interest.