Seaweed is a plant-like organism, which are adhered to rock or other hard substrata in coastal areas. Based on the pigmentation, seaweeds are categorized into three broad groups, red, brown, and green. Botanists refer to these broad groups as phaeophyceae, rhodophyceae, and chlorophyceae, respectively. Seaweeds are macro-algae that differentiate them from micro-algae, which are microscopic in size, and are often unicellular. Red and brown seaweeds are mostly found in marine water, whereas green seaweeds grow in freshwater. Seaweeds are used in many maritime countries across the globe as a source of human food, hydrocolloids, fertilizers, animal feed additives, and others, including aquaculture, biomass for fuel, and wastewater treatment. The major utilization of these seaweeds as food and food ingredients is in the Asia-Pacific region, particularly in China, Indonesia, Philippines, Korea, and Japan where seaweed cultivation has developed into a huge industry.