Amino acids are the building elements of proteins. Each protein has a very specific composition of amino acids. Thus, human protein differs from that of a plant or a fish in the structure of amino acids. Because our body consists largely of proteins and thus amino acids, we need amino acids every day.
In your body, not only your cells are made of protein, but amino acids are also needed for many other substances. So they play an absolutely crucial role in your whole body.
A distinction is made between essential and non-essential amino acids. Essential means that they cannot be formed in the body itself or by the microorganisms living in the digestive tract.