Algae form the primary link in the food chain. This means that our existence and that of all ocean and land animals depends on algae. Furthermore, with the abundance of many species of algae all over the globe, algae become part of our eco-system, and play an important role in global warming or its reversal. Algae can be divided into prokaryotes and eukaryotes. Each group exhibits enormous ecological, genotypic, and metabolic diversity with over 4000 distinct species of cyanobacteria (prokaryotes) and a similar number of unicellular algae (eukaryotes) classified so far. Algae can also be divided into macroalgae and microalgae. Macroalgae includes multicellular seaweed, whereas microalgae are microscopic. Microalgae proliferate under the right conditions in an unparalleled manner, so are considered to be the right candidate for a future food.