TITLE: A cardinality of a graph
QUESTION [11 upvotes]: If I have graph $G=(V,E)\\$
What is the meaning of $|G|$? (The cardinality of G).
I'd like to know few words about it.
Thank you!

REPLY [3 votes]: Usually
|V| = number of vertices or graph order.
|E| = number of edges or graph size.
Some like to use |G| to mean the graph order though.