the cambridge structural database (csd) is both a repository and a validated and curated resource for the three-dimensional structural data of molecules generally containing at least carbon and hydrogen, comprising a wide range of organic, metal-organic and organometallic molecules. the specific entries are complementary to the other crystallographic databases such as the protein data bank (pdb), inorganic crystal structure database and international centre for diffraction data. the data, typically obtained by x-ray crystallography and less frequently by electron diffraction or neutron diffraction, and submitted by crystallographers and chemists from around the world, are freely accessible (as deposited by authors) on the internet via the csd's parent organization's website (ccdc, repository). the csd is overseen by the not-for-profit incorporated company called the cambridge crystallographic data centre, ccdc.