Graphs are used in wide varieties of applications. Some of them are as follows:

*Social network graphs to determine the flow of information in social networking websites like facebook, linkedin etc.

- Neural networks graphs where nodes represent neurons and edge represent the synapses between them
- Transport grids where stations are the nodes and routes are the edges of the graph.
- Power or water utility graphs where vertices are connection points and edge the wires or pipes connecting them.
- Shortest distance between two end points algorithms.

Few important real life applications of graph data structures are:

- Facebook: Each user is represented as a vertex and two people are friends when there is an edge between two vertices. Similarly friend suggestion also uses graph theory concept.
- Google Maps: Various locations are represented as vertices and the roads are represented as edges and graph theory is used to find shortest path between two nodes.
- Recommendations on e-commerce websites: The “Recommendations for you” section on various e-commerce websites uses graph theory to recommend items of similar type to user’s choice.
- Graph theory is also used to study molecules in chemistry and physics.