From Academic Kids
In colloquial English, person is often synonymous with human. However, in philosophy, there have been debates over the precise meaning and correct usage of the word, and what the criteria for personhood are.
Are all persons human?
Firstly, there is the simple view that the common usage is the correct one: that person does indeed mean human. However, this runs into the problem that the term person has a somewhat loaded meaning - we commonly believe that all and only persons have certain rights, for example, the right to life. Some would go so far as to say that all and only persons are sacred. However, we can imagine the hypothetical alien from another planet, who, despite not being human, nevertheless has every trait that we see as being essential for this protected status that elevates it above mere objects. Thus, many claim that the simple view implies a sort of arrogant speciesism. There are also religious views that attribute personhood to supernatural beings (such as gods, angels, demons, elves, etc.) In fact, the present sense of the word person has developed in large part through reflection on the Trinitarian doctrine that God is one substance and three persons.
Are all humans persons?
Another problem with the simple view is that there are disputes over whether certain humans are persons. For example, in the abortion controversy, although the fetus is clearly of the human species, it is a matter of debate whether it is a person. Or in the case of a victim of severe brain damage who has no mental activity, some may claim that he or she is no longer a person, or that the person has ceased to exist, leaving only an "empty shell."
By some accounts, a person is one who, through his or her choices and decisions, has built a personal identity, which is active in further choices. A fetus has not yet had that opportunity (although the same could be said about a newborn child), and a severely brain-damaged person may no longer have the ability to act through further choices. On the other hand, Peter Kreeft, a professor of philosophy at Boston College, has argued that all humans beings are persons from conception.  (http://www.peterkreeft.com/topics-more/personhood.htm)
Criteria for personhood
The above points seem to indicate that there may be persons that are not human, and there may be humans that are not persons. For these reasons, many philosophers have tried to give a more precise definition, focusing on some trait or traits that all persons, real and hypothetical, must possess.
The most obvious such trait that persons typically possess is a conscious mind, typically (but not necessarily) with plans, goals, desires, hopes, fears, and so on. Yet the claim that such a mind is necessary for personhood is also problematic, as most would consider human babies as persons, yet their minds do not seem sufficiently advanced to satisfy this condition. A few philosophers have simply accepted that babies are not persons. However, most have not. Instead, some have suggested that the potential for such a mind is the correct trait.
Yet another view is that personhood is not all-or-nothing: there can be degrees of personhood, based on how close to a fully working mind the object in question has. Thus, a typical adult is entirely a person, while a human permanently in a coma is not a person at all. This view also seems to have some unpleasant consequences, for example, that a young child or someone with a moderate mental handicap might be, say, only half a person (and perhaps therefore have only half the rights, or be regarded as half as important). Jean Vanier, who has spent most of his life working and living with people with learning disabilities, has suggested that the capacity to be loved is what makes a true person.
It is probably true to say that other views also exist, and that the debate is not close to being resolved.
Moral rights and responsibility
Closely related to the debate on the definition of personhood is the relationship between persons, moral rights, and moral responsibility. Many philosophers would agree that all and only persons are expected to be morally responsible, and that persons deserve maximal moral rights. There is less consensus on whether only persons deserve moral rights and whether persons deserve greater moral rights than non-persons. The rights of non-person animals is an example of contention on this issue (see animal rights).
Corporations as persons
Largely separate from the discussion of "real" persons are considerations regarding artificial persons such as corporations and states. Under the Law of the United States, a corporation is considered a person for many legal purposes. Many question the wisdom of this legal fiction; the philosopher John Ralston Saul said, "If you are a person before the law and Exxon or Ford is also a person, it is clear that the concept of democratic legitimacy lying with the individual has been mortally wounded."
- "Human Personhood Begins at Conception" (http://www.peterkreeft.com/topics-more/personhood.htm) by Peter Kreeft, Castello Institutebn:ব্যক্তি