DNA barcoding aims to provide an efficient method for species-level identifications and, as such, will contribute powerfully to taxonomic and biodiversity research. As the number of DNA barcode sequences accumulates, however, these data will also provide a unique 'horizontal' genomics perspective with broad implications. For example, here we compare the goals and methods of DNA barcoding with those of molecular phylogenetics and population genetics, and suggest that DNA barcoding can complement current research in these areas by providing background information that will be helpful in the selection of taxa for further analyses.