The multitude of bacterial genome sequences being determined has opened up a new field of research, that of comparative genomics. One role of bioinformatics is to assist biologists in the extraction of biological knowledge from this data flood. Software designed for the analysis and functional annotation of a single genome have, in consequence, evolved towards comparative genomics tools, bringing together the information contained in numerous genomes simultaneously. This paper reviews advances in the development of bacterial annotation and comparative analysis tools, and progress in the design of novel database structures for the integration of heterogeneous biological information.