NOVEL TECHNOLOGIES IN the life sciences produce information at an accelerating rate, with public data stores (such as the one managed by the European Bioinformatics Institute http://www.ebi. ac.uk) containing on the order of 10PB of biological information. For nearly 40 years, the same was not so for chemical information, but in 2004 a large public small-molecule structure repository (PubChem http://pubchem. ncbi.nlm.nih.gov) was made freely available by the National Library of Medicine (part of the U.S. National Institutes of Health) and soon followed by other databases. Likewise, while many of the foundational algorithms of cheminformatics have been described since the 1950s, open-source software implementing many of them have become accessible only since the mid-1990s.