Most seaweeds algae species are mainly divided in three major groups.  These seaweed species included 32 Chlorophytes, 125 Rhodophytes and 64 Phaeophytes. The wild plant are growing attached to the rocky substrate.  Around twenty four economical important seaweed species are identified in Sri Lanka. The Ulva and caulipa are major available species belong to Chlorophytes. The economically important red algae species are Gracilaria and Kapphaphycus species. Some importance Brown algae species are Sagassum, Laminaria and fucus. These seaweeds are used to extraction of commercial impotent polysaccharides. The agar agar is extraction from Gracilaria and carrageenan from Kapphaphycus. The alginic acid extraction from Brown algae species. The main polysaccharides of agar, carrageenan and Alginic acid which is used as thickener, stabilize, emulsifier and also as functional food in processing industry. Gracilaria and carrageenan can reach relatively high gel strength by processing with treatments and is in high demand in the industry. Agar extraction residues contain good amount of organic matter and minerals and is used as bio fertilizer. Seaweed based foods have several health benefits and medicinal values.  These products are also available high iodine content. These foods are consumed as solution to several health problems in the digestive system and some nonpathogenic disease in human body