Personhood is the status of having outstanding moral worth. Yet the specific criteria that qualify someone as a person are controversial. In the West, personhood tends to be defined in terms of "sophisticated cognitive capacities;" yet, in other societies, such as sub-Saharan Africa, personhood is more often understood as a relational process. Defining personhood is a controversial topic in philosophy and law and is closely tied with legal and political concepts of citizenship, equality, and liberty. According to law, only a legal person (either a natural or a juridical person) has rights, protections, privileges, responsibilities, and legal liability.

Personhood continues to be a topic of international debate and has been questioned critically during the abolition of human and nonhuman slavery, in debates about abortion and in fetal rights and/or reproductive rights, in animal rights activism, in theology and ontology, in ethical theory, and in debates about corporate personhood, and the beginning of human personhood. In the 21st century, corporate personhood is an existing Western concept; granting non-human entities personhood, which has also been referred to a "personhood movement", can bridge Western and Indigenous legal systems.

Processes through which personhood is recognized socially and legally vary cross-culturally, demonstrating that notions of personhood might not be universal. Philosophers Nancy S. Jecker and Caesar A. Atuire have argued for a cross-border view of persons as emergent from social relational processes involving human beings. They write that a person "emerges out of a complex configuration of relationships involving human beings; we might say they become a ‘being-in-relationship.’ The emergent ‘being-in-relationship’ is a person, showing aspects, including superlative moral worth, not present before the relationships came together." Anthropologist Beth Conklin has shown how personhood is tied to social relations among the Wari' people of Rondônia, Brazil. Bruce Knauft's studies of the Gebusi people of Papua New Guinea depict a context in which individuals become persons incrementally, again through social relations. Likewise, Jane C. Goodale has also examined the construction of personhood in Papua New Guinea.

In philosophy, the word "person" may refer to various concepts. The concept of personhood is difficult to define in a way that is universally accepted, due to its historical and cultural variability and the controversies surrounding its use in some contexts. Capacities or attributes common to definitions of personhood can include human nature, agency, self-awareness, a notion of the past and future, and the possession of rights and duties, among others.

Boethius, a philosopher of the early 6th century CE, gives the definition of "person" as "an individual substance of a rational nature" ("Naturæ rationalis individua substantia").

According to the naturalist epistemological tradition, from Descartes through Locke and Hume, the term may designate any human or non-human agent who possesses continuous consciousness over time; and is therefore capable of framing representations about the world, formulating plans and acting on them.

According to Charles Taylor, the problem with the naturalist view is that it depends solely on a "performance criterion" to determine what is an agent. Thus, other things (e.g. machines or animals) that exhibit "similarly complex adaptive behaviour" could not be distinguished from persons. Instead, Taylor proposes a significance-based view of personhood:

What is crucial about agents is that things matter to them. We thus cannot simply identify agents by a performance criterion, nor assimilate animals to machines... [likewise] there are matters of significance for human beings which are peculiarly human, and have no analogue with animals.