Algae are a diverse group of photosynthetic organisms that can easily grow in marine, fresh-, and wastewater environments. About 90% of marine plants are algae that efficiently convert carbon dioxide into sugars and oxygen, hence being responsible for more than 50% of the global carbon fixation and oxygen production. There are more than 200,000 different algal species, but only approximately 200 species are currently used worldwide in different sectors. Since algae produce a wide range of metabolites such as lipids (oil), proteins, carbohydrates (sugars), carotenoid pigments, minerals, vitamins, and bioactive polyphenols, they have been used as food, feed, and fertilizers for centuries. Recently, their potential for making ethanol or biodiesel has projected them as living-cell factories for the production of biofuels and various beneficial bioactives used in pharmaceuticals and cosmetics. This chapter outlines the potential of algae for food, feed, and fuel applications along with the importance of algal strain selection for individual applications.