Protein is a vital macronutrient made up of long chains of amino acids. It plays a crucial role in building and repairing tissues, making enzymes and hormones, and supporting overall bodily functions. Foods rich in protein include meat, fish, eggs, dairy products, and legumes. The body requires protein for growth and maintenance, making it essential for everyone, especially for children, athletes, and those recovering from illness. Proteins can be classified into two categories: complete proteins, which contain all essential amino acids, and incomplete proteins, which lack one or more essential amino acids.