Social organisms, including human(s), live collectively in interacting populations. This interaction is considered social whether they are aware of it or not, and whether the exchange is voluntary or not.
The word "social" derives from the Latin word socii ("allies"). It is particularly derived from the Italian Socii states, historical allies of the Roman Republic (although they rebelled against Rome in the Social War of 91–87 BC).
In the view of Karl Marx, human beings are intrinsically, necessarily and by definition social beings who, beyond being "gregarious creatures", cannot survive and meet their needs other than through social co-operation and association. Their social characteristics are therefore to a large extent an objectively given fact, stamped on them from birth and affirmed by socialization processes; and, according to Marx, in producing and reproducing their material life, people must necessarily enter into relations of production which are "independent of their will".
By contrast, the sociologist Max Weber for example defines human action as "social" if, by virtue of the subjective meanings attached to the action by individuals, it "takes account of the behavior of others, and is thereby oriented in its course".
In contemporary society, "social" often refers to the redistributive policies of the government which aim to apply resources in the public interest, for example, social security. Policy concerns then include the problems of social exclusion and social cohesion. Here, "social" contrasts with "private" and to the distinction between the public and the private (or privatised) spheres, where ownership relations define access to resources and attention.
The social domain is often also contrasted with that of physical nature, but in sociobiology analogies are drawn between humans and other living species in order to explain social behavior in terms of biological factors.