Social Relationships connote association, co-operation, mutual dependence and belonging. It could be argued that a social relationship is, in the first instance, simply a relation between people, but more specifically
a relation between individuals insofar as they belong to a group
a relation between groups of people, or
a relation between an individual and a group of people.
The group could be an ethnic or kinship group, a social institution or organisation, a social class or social stratum, a nation, a population, or a gender etc. This definition contrasts with the relationship between people and inanimate objects.
Some individuals may also be socially related in many different ways, insofar as members of the same or different social groups, and thus their identity is shaped in good part by the fact that they belong to those groups. If we wanted to understand and explain their behaviour, we would need to refer to those social relations and social relationships. We might establish the milieu they grew up in, their ancestors, the jobs they do, where they lived, who their friends are, and so on, all of which helps explain why they necessarily interact in the way that they do, and not in some other way.
At a higher level of abstraction, we might consider two groups which are socially related, for example, although they live in different places, they depend on each other in trading goods and services. At an even higher level of abstraction, we might consider the relationship between an individual and the whole of the world population, or the relationship of the world population to itself.