Graph Concept

In computer science, a graph is an abstract data structure that is meant to implement the graph and hypergraph concepts from mathematics. A graph data structure consists of a finite (and possibly mutable) set of ordered pairs, called edges or arcs, of certain entities called nodes or vertices. As in mathematics, an edge (x,y) is said to point or go from x to y. The nodes may be part of the graph structure, or may be external entities represented by integer indices or references.

A triples statement in RDF is one such building block of these graph structures. The "barbell" aspect of node - edge - node is more formally a subject - predicate - object triple in RDF. As these "barbell" statements get combined together, a graph structure begins to emerge.