Article says that horizontal gene transfer (HGT) is a major source of phenotypic innovation and a mechanism of niche adaptation in prokaryotes. Methods for detecting HGT can be classified into phylogenetic-based and parametric or composition-based approaches, so authors exploited the complementary strengths of both the approaches to construct a high confidence horizontal gene flow network. The scale-free horizontal gene flow network presented here provides new insights into modes of transfer for the exchange of genetic information and also illuminates differential gene flow across phyla.