What does a Graph consist of?

When is a Graph a Directed Graph?
(or a Digraph)

When is a Graph an Undirected Graph?

If it is not specified whether a graph is Directed or Undirected, what is it assumed to be?

What is a Path in a Graph?

What is a Cycle in a Graph?

What is a Loop in a Graph?

What is the Degree of a Vertex?

What is a Connected Graph?

What is a Weighted Graph?