Social relations are defined by considering the different dimensions involved: interaction, knowledge, emotional involvement, and, more generally, the "driving force" of the tie, which are its essential elements. This characterization of relationships is continued by mentioning qualities that are very important for their becoming: the multiplexity and "strength" of the ties. To explain the link between relationships, networks, and social circles, the different scales at which the entourage can be considered are then evoked. The questions of the homogeneity of relationships, the resources they may constitute, as well as the different ways in which they can be inscribed in social circles are also addressed. Finally, the various types of regulation involved in the positioning of relationships are presented.