Book excerpt: Diatoms are the most species rich group of algae, and they contribute about 20% of annual global carbon fixation. They play major roles in ocean food webs and global biogeochemical cycles. They are also a target of the biotechnology industry because of their nano-patterned silica cell wall and high lipid content. Diatoms have received increasing attention as more genomes became available and because of the development of genome editing tools such as the CRISPR/Cas9 technology, which has made diatoms as genetically tractable as well-established biological model species. This book provides an overview on diatom molecular biology. It brings together international leading experts in the field to discuss the latest data and developments from genes to ecosystems. As the understanding of diatoms is currently experiencing a step change, it is critical to allow for synergistic approaches on diverse aspects of diatom biology and evolution. The books offers fundamental insights into the molecular life of diatoms; at the same time new scientific concepts are developed based on the application of the latest molecular tools and genomic information to explore the fascinating lifestyle of diatoms.