A literal definition of an Amino acid is an organic compound containing an amino group (-NH2) and a carboxyl group (-COOH). So what does this mean? It means they are literally the building blocks for all life, in that they are the chemical basis for all protein. Protein is one of the biggest components of our bodies (as well as the bodies of all living things). Our bodies use amino acids to form the proteins which build everything from muscles and bones, skin and hair, to internal organs and fluids. These amino acids also play an active role in our nervous system, where they function as neurotransmitters carrying messages from cell to cell. In short, amino acids are absolutely essential for our well-being.