Simple graph- every edge is connected to two different vertices; no two edges can be connected to the same pair of vertices.
Pseudograph- may consists of multiple edges (loops) and are also non simple.
There are many types of graphs
when looking into graph theory. Some of the two basics are directed and
undirected. A directed graph is a graph that contains edges connected by one
vertex to the next. An undirected graph however, has vertices that are
connected by edges that are bidirection.