EdgeQ
(Built-in Mathematica Symbol) EdgeQ[g, e] yields True if e is an edge in the graph g and False otherwise.
LineGraph[g] gives the line graph of the graph g.
SimpleGraph[g] gives the underlying simple graph from the graph g.
DepthFirstScan[g, s, {"event_1" -> f_1, "event_2" -> f_2, ...}] performs a depth-first scan of the graph g starting at the vertex s and evaluates f_i whenever "event_i" ...
VertexCount[g] gives a count of the number of vertices in the graph g.VertexCount[g, patt] gives a count of the number of vertices that match the pattern patt.
EdgeCount[g] gives a count of the number of edges in the graph g.EdgeCount[g, patt] gives a count of the number of edges that match the pattern patt.
FindShortestPath[g, s, t] finds the shortest path from source vertex s to target vertex t in the graph g.FindShortestPath[g, s, All] generates a ShortestPathFunction[...] ...
GraphDistance[g, s, t] gives the distance from source vertex s to target vertex t in the graph g.GraphDistance[g, s] gives the distance from s to all vertices of the graph g.