A graph-traversal algorithm visits (exactly once) all those vertices of a graph which are reachable from a given set of seed vertices . The order in which the vertices are visited depends on the specific algorithm.
A specific graph traversal algorithm is encapsulated by an 
algorithm-object implementing the GraphTraversal 
concept. An algorithm-object of this type can be executed by
the traverseGraph() function implemented in 
generic_traversal.h.