Many networks emerge as the outcome of a collective interaction, like the WWW; others are the consequence of the biological evolution, like the brain. In contrast to these examples, we investigate the topology of trees generated by single individuals. Computer users generate directory structures to store and manage information in files. Analyzing the directory and file-trees generated by different users we have access to different realizations available for statistical analysis. We characterize the architecture of directories and files created by different computer users by means of the degree distributions and number of leaves, degree-degree correlations, average distance to the root, and community size distributions. We compare the different topologies in the search for similar managing patterns, and compare the trees obtained with two simple models of growing networks and with a model that interpolates between them and incorporates the heterogeneity of the computer users.

We acknowledge financial support from MCyT (Spain) through project CONOCE2, from Dutsche Forschungsgemeinschaft through Bioinformatics Initiative BIZ-6/1-2 and from Deutscher Akademischer Austauschdienst (DAAD).

7 pages, 6 figures.-- Printed version published Dec 2006.-- Issue title: "Dynamics on Complex Networks and Applications".

Full-text paper available Open Access at: http://ifisc.uib-csic.es/~victor/Filetrees/filetrees_PD.pdf