Algae are relatively undifferentiated organisms which, unlike plants, have no true roots, leaves, flowers or seeds. They are found in marine, freshwater and terrestrial habitats. Secondary metabolites are organic compounds that are not directly involved in the normal growth, development, or reproduction of an organism. Secondary metabolites often play an important role in plant defense against herbivory and other interspecies defenses. To survive in a competitive environment, freshwater and marine algae have developed defense strategies that result in a significant level of structural–chemical diversity, from different metabolic pathways. The marine algae produce these secondary metabolites so as to protect themselves from the marine organisms which come to attack or consume. These secondary metabolites acts a defense mechanism and stops them from being attacked or consumed.

Every organism produces secondary metabolites in some way or the other for the defense mechanism. These secondary metabolites can be used for various purposes like drugs, industrial products and varies other things. They are very useful products.