The book commences with a comprehensive examination of cyanobacterias fossil record. It offers an extensive analysis of the antibacterial properties of cyanobacteria, based on extensive research conducted by the author. The book also sheds light on other aspects of cyanobacterias biological activity, such as anti-fungal, anti-HIV, proteinase inhibitor, anti-mycobacterial, anti-helmintics, anti-inflammatory, cytotoxic, and anti-cancer characteristics. The book provides a comprehensive monograph on nine cyanobacterial species, including Anabaena variabilis, Anabaena fertilissima, Nostoc muscorum, Nostoc punctiforme, Nostoc linckia, Nostoc commune, Spirulina platensis, Westiellopsis prolifica, and Hapalosiphon sp. The book is written in a clear and concise manner, with explanatory diagrams to aid in comprehension. The volume also includes a glossary of technical terms and a comprehensive list of references and index for the readers convenience. Overall, this book will be a valuable resource for research students, teachers, and professionals in the fields of microbiology, medicine, and pharmaceutical sciences, as well as pharmaceutical industries for R&D related to drug discovery.