Phycoerythrin is a major light-harvesting pigment belonging to Phycobiliproteins of red algae. R-PE is commonly used as a fluorescent label in immunology and cell biology and in flow cytometry. It is also used as a natural food dye and as a marker in gel electrophoresis and iso-electrofocusing. The main applications of phycobiliproteins are as fluorescent markers of cells and macromolecules in biomedical research and natural colorant in food and cosmetics. Phycobiliproteins are largely appreciated for their immuno-enhancing, anti-inflammatory, anti-carcinogenic, antioxidant and nutritive values. This book throw light on the beneficial activities of this macroalgae which is not unravelled so far.