“Organic matter” (organic material) is a collective term for all carbon-based chemical compounds (with the exception of carbon oxides CO2 and CO, as well as carbonates and carbide). Their properties, structures and reactions are the subject of organic chemistry and – if they occur in living nature – of biochemistry. There are two reasons for the diversity of the well over one million known organic compounds: in addition to the tetravalent nature of the carbon atom, it is above all its tendency to form chains, branches or rings - in large numbers and in manifold ways with its equals. About 90 percent of all organic compounds consist of carbon, hydrogen and oxygen. Nitrogen, phosphorus, sulfur and the halogens (bio elements) are less frequently involved. Organic compounds with metals are referred to as metal-organic compounds. Important representatives of this group, which are found in the animal kingdom, are heme and heme group carrying proteins, chlorophyll and cobalamin. The term “organic compound” goes back to the earlier idea that only organisms are able to produce these substances because of their special vital force. The mistake was recognized in 1824 when Friedrich Wöhler succeeded in synthesizing oxalic acid.