To understandsocial network analysis (SNA), you must understand what a social network is, and what a social graph is. Simply put, SNA is the analysis of social networks and a social network is just a network ofentities that are connected by therelationship among the entities. This concept has existed since humans began walking the earth. In fact, social networks exist even in manysocial animals beside humans (e.g. wolves, lions, dolphins, bats, and even ants).
Of course, the entities that interest us are people, and the relationships that are of particular interest include friendships (as inFacebook), colleagues (as inLinkedIn), kinship, communications, and several other social interactions. And in the context of SNA, you can think of a social graph as simply a diagram that represents the social network (I am not going to bore you with the formal definition of agraph). In a social graph, each dot (a.k.a. node or vertex) represents a person, and an edge between two dots (persons) represents a relationship between them. As there are many complex relationships among people, there are equally many different social graphs that represent these relationships. I will illustrate this with an example.
A Representative Social Network and Its Social Graphs
Let’s suppose that I, Michael, have a very small social network consisting of only seven friends (see the names in figure 1). Suppose I have a very simple life, and I only have three types of social relationships in my life: colleagues at work (denoted by the red edges), beer buddies (blue edges), and badminton pals (green edges).