Seaweeds are plant- like ocean organisms that are botanically classified as macrophytic marine algae. Edible seaweeds are often called sea vegetables. Seaweeds come in an amazing variety of beautiful shapes, colours and sizes and found in all of the world’s oceans. Seaweeds generally thrive attached to rocks or other hard substrate in coastal areas. The classification into divisions is based on various properties such as pigmentation, chemical nature of the photosynthetic storage product, the organization of photosynthetic membranes and other morphological features.

               A number of research studies have shown that the chemical composition of the macro algae varies depending on the geographical distribution, habitats, maturity, seasons and the principal environmental conditions, such as water, temperature, salinity, light and nutrients.
About 250 macro algal species have been commercially utilized worldwide and about 150 species are favorably consumed as human food. Approximately 841 taxa of marine algae were found in both intertidal and deep water regions of the Indian coast. Seaweeds are reported to be rich in soluble dietary fiber, protein, minerals, vitamins, antioxidants, phytochemical and polyunsaturated fatty acids with low calorific value.

               Seaweeds possess a great variety of bioactive compounds characterized by a broad spectrum of biological activities. Compounds isolated from marine macro algae have demonstrated various biological activities such as antibacterial, antioxidant, anti- inflammatory properties, anticoagulant, antiviral and apoptotic activity. The antioxidant activity of seaweeds are from pigments such as chlorophylls, carotenoids, vitamins and their precussors, including beta-carotene, α- tocopherol, niacin, thiamin, ascorbic acid and phenolic compounds such as polyphenolic, hydroquinones, flavonoids and phospholipids particularly phosphatidylcholine, terpenoids, peptides and other bioactive substances which directly or indirectly contribute to the inhibition or suppression of oxidative processes. Seaweeds contain a prolific source of bioactive components that can be used as bio-preservative to enhance the shelf life  of fruits and vegetables. Due to the presence of growth hormones like auxin and gibberellins and efficient bioactive compounds, seaweeds are utilized to produce plant growth promoters and biopesticides.