%X We show that the PageRank in a network can be represented as the solution of a differential equation discretized over a directed graph. By exploiting a formal relationship with the time-independent Schr?dinger equation it is possible to interpret hub formation and related phenomena as a wave-like localization process in the presence of disorder and trapping potentials. The result opens new perspectives in the physics of networks with interdisciplinary connections and opens the way to the employment of various mathematical techniques to the analysis of self-organization in structured systems. Applications are envisaged in the World-Wide Web, traffic, social and biological networks. %T PageRank equation and localization in the WWW %J EPL (Europhysics Letters) %V 88 %N 4 %D 2009 %L eprints1083 %A Nicola Perra %A Vinko Zlatic %A Alessandro Chessa %A Claudio Conti %A Debora Donato %A Guido Caldarelli %R doi:10.1209/0295-5075/88/48002 %K PACS 71.23.-k Electronic structure of disordered solids; 89.75.Fb Structures and organization in complex systems; 05.10.-a Computational methods in statistical physics and nonlinear dynamics %P 48002 %I IOPscience