The nodes adjacent to the current node.
Directed Graph
Out Neighbourhood
The list of nodes that the current node links to
In this case for node B, it is: [C,D]
In Neighbourhood
The list of nodes that the current node is linked from
In this case for node B, it is: [A]
Self-Linking Node
For a self-linking node, it is included within its neighbourhood set. Both in out neighborhood and in neighborhood.