The carotenoids are a class of natural pigments that is very widespread and it was demonstrated that they occur in all the three domains of life, i.e. in the eubacteria, the archea and in the eucarya. Rich sources for carotenoids are the algae and more than 100 carotenoids have been isolated and characterized from these organisms. For humans the most important source for carotenoids are plants, where often the brilliant colors of the carotenoids are masked by chlorophyll, e.g. in green leaves. The carotenoids are responsible for the colors of many fruits (pine-apple, citrus fruits, tomatoes, paprika, rose hips) and flowers (Eschscholtzia, Narcissus), as well as the colors of many birds (flamingo, cock of rock, ibis, canary), insects (lady bird), and marine animals (crustaceans, salmon).