The primary source of protein in the human diet largely comes from animal products, including meat, fish, eggs, and dairy. These sources provide complete proteins, containing all essential amino acids required for bodily functions. However, plant-based proteins, found in legumes, nuts, seeds, and whole grains, are also significant components of many diets. While some plant proteins may be incomplete, consuming a variety of plant sources can provide the necessary amino acids. Understanding the sources of protein is crucial for nutrition, as proteins play essential roles in building tissues, enzymes, and hormones necessary for health and well-being.