The final data structure that we will examine is the **Graph**. Graphs are sets of objects with no specifically structured relationship, where each object can have links to one or many other objects in the collection. Objects in graphs are typically referred to as nodes, vertices, or points. Links, or the relationships between the objects, are referred to as edges, lines, or arcs. These links can be simple references or they can be objects with values of their own. More formally stated, graphs are a pair of sets *(N, E)*, where *N* is the set of nodes and *E* is the set of edges in the collection.

One excellent example of graph applications would be visualizing the relationships between individuals in a social media database. In such a database, each person in the database represents one node, and each of their links to other people in their circle of acquaintances represents an edge. In such a circle of acquaintances, it would be perfectly reasonable to...