Databases are critical to all scientific endeavours. They manage our email, funding, and scientific literature, and provide access to the ever-growing mountains of scientific data. In molecular virology, all researchers are familiar with performing BLAST searches of the DNA and protein sequence databases; however, in some respects these are simple databases tailored to this specific task. This collection of virus databases illustrates a greater diversity of purpose, but reveals they often function to support only one or a few virus families grouped by a common theme. The common characteristic is usually genome size as small RNA viruses are typically sequenced in vastly greater numbers and are much less complex than the large DNA viruses; they have variability at the level of SNPs rather than gene presence/absence. Here, we present the basics of database organization and aim to compare and contrast these features and the manner by which the databases are used by the scientific community.