The article analyzes numerous facts that among various species of algae cultivated by humans, Chlorella takes the leading position, ahead of the popular brown algae (kelp) and red algae (nori). Chlorella species Chlorella vulgaris is especially widely used, which has a rich content of biologically active substances and is able to produce large amounts of biomass quickly. Chlorella applications are common in agriculture, food production, medicine and cosmetology, wastewater treatment and health improvement of water bodies, as well as in the production of biofuels and oxygen. As a food additive, chlorella is already widely used around the world, despite the fact that it was recently popular only in Japan. Chlorella microalgae also finds applications in biotechnology for the production of proteins and vitamins.