Cyanoprokaryotes are probably the oldest organisms with plant metabolism. However, their cell structure and type of asexual reproduction prove their eubacterial origin. In spite of their existence from Precambrian onwards they have not lost their vitality, and still are able to colonize all possible biotopes, including very extreme environments (thermal springs up to 80 C, rocks in extremely hot or cold deserts in both the tropics and Antarctica, hypersaline lakes and marshes, biotopes in volcanic regions, and other harsh habitats). This book is a review of all the cyanoprokaryotic taxonomic...