In general, a network is yet another—relational—form of organization and representation of discrete data. (The other one being tabular, with the data organized in rows and columns.) Two important network concepts are entities and the relationships between them. Depending on a researcher’s background, entities are known as nodes (the term we’ll use in this book), actors, or vertices. Relationships are known as edges (preferred in this book), links, arcs, or connections. We will casually refer to networks as “graphs” (in the graph-theoretical meaning of the word), even though graphs are not the only way to describe networks.
Graphs and Graphs
When it comes to mathematics, the word “graph” has at least two different meanings. ...