“1) “Social networks are formally defined as a set of nodes (or network members) that are tied by one or more types of relations.”

2) “A social network is the pattern of friendship, advice, communication or support which exists among the members of a social system.””

References

“1) Wasserman, S. and Faust, K., 1994. Social network analysis: Methods and applications (Vol. 8). Cambridge university press.

2) Valente, T. W., 1996. Social Network thresholds in the diffusion of innovations. Soc. Netw. 18, 69–89. https://doi.org/10.1016/0378-8733(95)00256-1“