In relation to bodybuilding, protein is viewed as a key nutrient in the development of strength and size. Anecdotally most bodybuilders would say that the more protein the better, on the other hand most sports dieticians take the opposite view in that protein is abundant in the average diet and if energy requirements are meet there's a good chance that protein requirements will also.
Protein is essential for life. It provides the building blocks for tissue, hormones, enzymes and accounts for 15% of the body. The building blocks it provides are amino acids and different proteins provide different amino acids and ratios of amino acids.