This report provides a comprehensive overview of protein, a crucial macronutrient essential for various bodily functions. It begins with an introduction to macronutrients and highlights the significance of protein in building and repairing tissues, as well as its role in maintaining muscle mass and overall health. The report delves into the composition of protein, explaining how amino acids form polypeptide chains and the different types of proteins. It then explores the biological functions of protein, including its role in catalyzing reactions, transporting molecules, supporting the immune system, and acting as a source of energy. The report further discusses the dietary sources of protein, including meat, dairy, nuts, and legumes. It also covers the recommended daily intake of protein and factors that influence individual needs. Finally, the report examines the factors contributing to both excess and insufficiency of protein, as well as the signs and symptoms associated with these conditions, concluding with a summary of the key findings.