Table 1.

Top-level structure of real-world networks

Network	Nodes	Edges	Modules	Main modules
Air transportation	3,618	28,284	57	8
E-mail	1,133	10,902	41	8
Electronic circuit	516	686	18	11
Escherichia coli KEGG	739	1,369	39	13
E. coli UCSD	507	947	28	17

We show both the total number of modules and the number of main modules at the top level. Main modules are those composed of more than 1% of the nodes. Note that there is no correlation between the size or number of edges of the network and the number of main modules. KEGG, Kyoto Encyclopedia of Genes and Genomes; UCSD, University of California at San Diego.