Book excerpt: Owing to their importance as primary producers of energy and nutrition, algae and cyanobacteria are found as symbiotic partners across diverse lineages of prokaryotic and eukaryotic kingdoms.Algal and Cyanobacteria Symbioses presents a compilation of recent, updated research in fields of diverse symbioses, including in marine, freshwater, and terrestrial habitats. It gives a comprehensive overview of algal and cyanobacteria symbioses, including reviews on their diversity and information on symbiotic specificity and stress tolerance. Also covered is a review of regulatory mechanisms in the communication between symbiotic partners.The highly interdisciplinary character of this book is demonstrated through the range of algae and cyanobacteria as energy-providing symbionts in organismal lineages which are discussed. It is a valuable source of knowledge for researchers, university lecturers, professors and students of biology and life sciences, specifically biochemistry, mycology, cell biology and plant-microbe interactions.