Polysaccharides are long polymeric chains of carbohydrates. They are composed of monosaccharide units which are linked together by glycosidic linkages. These biomolecules react with water to form constituent sugars. Marine polysaccharides are carbohydrates of marine origin. These are sulfated polysaccharides which are produced by concomitant fixation of sulphur and carbon. Some common examples of marine polysaccharides are chitosan, chitin, carrageenan, fucoidan and alginate. These carbohydrates are gaining popularity as they have low extraction cost and are soluble in aqueous solution and extraction media. Seaweeds and exoskeletons of crustaceans are some of the major resources of marine polysaccharides. They find extensive application in the field of pharmaceuticals, nutraceuticals, cosmeceuticals and tissue engineering. There has been rapid progress in this field and its applications are finding their way across multiple industries. The various advancements in the study of marine polysaccharides are glanced at and their applications as well as ramifications are looked at in detail. The topics covered in this book offer the readers new insights on marine polysaccharides.