In a network, the shortest path between two nodes i and j, is the path requiring the smallest number of steps to reach j from i, following edges in the network. There may be (and often there is) more than one shortest path between a pair of nodes. The distance between any pair of nodes d i, j is the minimal number of steps required to reach j from i, that is, the number of steps in the shortest path. The average distance, d is the mean of the distances between all pairs of nodes and measures the typical distance between nodes