The **webgraph** describes the directed links between pages of the World Wide Web. A graph, in general, consists of several vertices, some pairs connected by edges. In a directed graph, edges are directed lines or arcs. The webgraph is a directed graph, whose vertices correspond to the pages of the WWW, and a directed edge connects page X to page Y if there exists a hyperlink on page X, referring to page Y.

## Properties

- The degree distribution of the webgraph strongly differs from the degree distribution of the classical random graph model, the Erdős–Rényi model:
^{[1]}in the Erdős–Rényi model, there are very few large degree nodes, relative to the webgraph's degree distribution. The precise distribution is unclear,^{[2]}however: it is relatively well described by a lognormal distribution, as well as the Barabási–Albert model for power laws.^{[3]}^{[4]} - The webgraph is an example of a scale-free network.

## Applications

The webgraph is used for:

- computing the PageRank
^{[5]}of the WWW-pages; - computing the personalized PageRank;
^{[6]} - detecting webpages of similar topics, through graph-theoretical properties only, like co-citation;
^{[7]} - and identifying hubs and authorities in the web for HITS algorithm.

## References

**^**P. Erdős, A. Renyi,*Publ. Math. Inst. Hung. Acad. Sci.*5 (1960)**^**Meusel, R.; Vigna, S.; Lehmberg, O.; Bizer, C. (2015). "The Graph Structure in the Web - Analyzed on Different Aggregation Levels" (PDF).*Journal of Web Science*.**1**(1): 33–47. doi:10.1561/106.00000003. hdl:2434/372411.**^**Clauset, A.; Shalizi, C. R.; Newman, M. E. J. (2007). "Power-law distributions in empirical data".*SIAM Rev*.**51**(4): 661–703. arXiv:0706.1062. Bibcode:2009SIAMR..51..661C. doi:10.1137/070710111.**^**Barabási, Albert-László; Albert, Réka (October 1999). "Emergence of scaling in random networks" (PDF).*Science*.**286**(5439): 509–512. arXiv:cond-mat/9910332. Bibcode:1999Sci...286..509B. doi:10.1126/science.286.5439.509. PMID 10521342..**^**S. Brin, L. Page, Computer Networks and ISDN Systems 30, 107 (1998)**^**Glen Jeh and Jennifer Widom. 2003. Scaling personalized web search. In Proceedings of the 12th international conference on World Wide Web (WWW '03). ACM, New York, NY, USA, 271–279. doi:10.1145/775152.775191**^**Kumar, Ravi; Raghavan, Prabhakar; Rajagopalan, Sridhar; Tomkins, Andrew (1999). "Trawling the Web for emerging cyber-communities".*Computer Networks*.**31**(11–16): 1481–1493. CiteSeerX 10.1.1.89.4025. doi:10.1016/S1389-1286(99)00040-7.

## External links

- Webgraphs in Yahoo Sandbox
- Webgraphs at University of Milano – Laboratory for Web Algorithmics
- Webgraphs at Stanford – SNAP
- Webgraph at the Erdős Webgraph Server
- Web Data Commons - Hyperlink Graph