Directed and undirected graphs
Graphs can be classified based on whether they are undirected or directed. An undirected graph simply represents edges as lines between the nodes. There is no additional information about the relationship between the nodes than the fact that they are connected:
In a directed graph, the edges provide orientation in addition to connecting nodes. That is, the edges, which will be drawn as lines with an arrow, will point in which direction the edge connects the two nodes:
The arrow of an edge determines the flow of direction. One can only move from A to B in the preceding diagram. Not B to A.
