Graph
Consists of a finite set of vertices connected by edges
Edge
Joins one vertex to another
Loop
Where an edge starts and ends at the same vertex
Multiples edges
When there is more than one edge joining the same pair of vertices
Simple graph
there are no loops or edges
Connected graph
Every vertex is linked by a single edge
Completed graph
Simple graph where every vertex is connected to every other by a single edge
Degree
Number of edges that start or finish at a vertex
Handshaking theorem
Total degrees of vertices = 2 x edges
Digraph
When the edges of a graph have a direction associated with them
Subgraph
Part of a graph which is a graph in itself