Applications of graph?

Some of the popular applications are as follows:

• Model of www: The model of world wide web (www) can be represented by a collection of graphs (directed) wherein nodes denote the documents, papers, articles, etc. and the edges represent the outgoing hyperlinks between them.
• Railway system: The cities and towns of a country are connected through railway lines. Similarly, road atlas can also be represented using graphs.
• Airlines: The cities are connected through airlines.
• Resource allocation graph: In order to detect and avoid deadlocks, the operating system maintains a resource allocation graph for processes that are active in the system.
• Electric circuits: The components are represented as nodes and the wires/connections as edges.