Microalgae are used as food, feed, and fodder and also used to produce a wide range of metabolites such as, proteins, carbohydrates, lipids, carotenoids, vitamins, fatty acids, sterols, etc. They are able to enhance the nutritional content of conventional food and feed preparations and hence positively affect humans and animal health including aquaculture animals. They also provide a key tool for phycoremediation of toxic metals and nanometal production. The use of microalgae in nanotechnology is a promising field of research with a green approach. The use of genetically modified algae for better production of different biotechnological compounds of interests is popular nowadays. Microalgal biomass production for sustainable biofuel production together with other high-value compounds in a costeffective way is the major challenge of algal biotechnologists. Microalgal biotechnology is similar to conventional agriculture but has received quite a lot of attention over the last decades, because they can reach substantially higher productivities than traditional crops and can use the wastelands and the large marine ecosystem. As history has shown, research studies on microalgae have been numerous and varied, but they have not always resulted in commercial applications. The aim of this review is to summarize the commercial applications of microalgae. © Springer India 2015.