The Trail inert function is used as a short form description of edges in a graph passing through a vertex sequence/list in the given order. For example, Trail(1,2,3,4) or Trail([1,2,3,4]) are short form to specify a trail through the vertices that generates the edges ,  and .

The Trail function is only understood by the functions that construct graphs (Graph and Digraph) as well as functions that add edges to a graph or remove edges from a graph (AddEdge, DeleteEdge, AddArc, and DeleteArc). It is also used as a return value for a specified path (IsEulerian).