Biodiversity 1s a term commonly used to denote the variety of species and the multiplicity of forms of life. But this variety is deeper than is generally imagined. In addition to the processes of primary metabolism that involve essentially the same chemistry across great swathes of life, there are a myriad of secondary metabolites-natural products-usually confined to a particular group of organisms, or to a single species, or even to a single strain growing under certain conditions. In most cases we do not really know what biological role these compounds play, except that they represent a treasure trove of chemistry that can be of both interest and benefit to us. Tens of thousands of natural products have been described, but in a world where we are not even close to documenting all the extant species, there are almost certainly many more thousands of compounds waiting to be discovered.