The key to fully harnessing the ever expanding amount of genome sequence data is in the development of well-structured databases and tools to provide complex access for the user. The author gives a good general introduction to the science of genome sequencing, assembly and annotation, followed by chapters describing and comparing by defined example two of the major genome databases available (UCSC's genome browser and EBI's Ensembl) with a brief mention of MapViewer at NCBI (At the current time these databases do not contain any microbial genomes, but that is likely to change in the near future). The target audience is probably set by the later chapters describing detailed examples of accessing these databases programatically, such that the interested reader would have to have a reasonable understanding of the programming languages Perl and C. The book would suit a bioinformatician wishing to gain an introduction into genome database querying and interaction.