Book excerpt: In one convenient source, this ready reference brings together for the first time, all the information available on various cyanobacterial symbioses/symbiotic cyanobacteria. Comprehensive data on structure, physiology, biochemistry and molecular biology of the cyanobiont in various cyanobacterial symbioses is included. Aplied aspects such as use of Azolla in rice cultivation and artificial symbioses are addressed, along with a chapter dedicated to methodology. This informative new text is useful to researchers, teachers, and students.