One of the most daunting aspects of using genomic technologies—including microarray, proteomic, metabolomic, and other approaches—is the sheer quantity of data that they produce. With thousands of biologically relevant molecules surveyed across (increasingly) large numbers of samples, interpretation of the data requires the use of computational approaches. And while many researchers thought that storing the data could simply build on our experiences with genome sequencing, it quickly became apparent that if one was to make sense of the results from any analysis, there was a need to store much more complex ancillary data than would be necessary for genome sequence.

The International Working Group on Taxonomic Databases is a not for profit scientific and educational association, affiliated to the International Union of Biological Sciences, formed to establish international collaboration among biological database projects so as to promote the wider and more effective dissemination of information about the World's heritage of biological organisms for the benefit of the world at large.

An ontology is a domain of knowledge structured through formal rules so that it can be interpreted and used by computers. Ontologies are becoming increasingly important in bioinformatics because they can be linked to the information in databases and their knowledge then used to query the databases. Typical examples in current use are the Gene Ontology, which incorporates much of our knowledge about gene products, and ontologies of developmental anatomy, which, for example, facilitate tissue-based queries to gene expression databases both textually and spatially. This article considers the production, formulation and types of bio-ontologies together with the reasons why they are so useful.