Examples of things that can be represented as graphs:

	Vertices	Edges
FWGC Problem	States	Moves
Maps	Cities	Roads
Circuits	Transistors	Wires
Networks	Computers	Cables
Social Networks	People	Relationships
UML Diagrams	Classes	Class Relationships
JavaFX Scene	Nodes	Hierarchy Relationships

Trees (for example, binary search trees) are special cases of graphs.