Well, ten out of the 20 amino acids used by the cells of our body are actually synthesized inside our cells. So we can synthesize amino acids, ten amino acids from scratch, but the other ten amino acids are called essential amino acids. And that's because we cannot actually synthesize those ten amino acids. These ten essential amino acids are obtained from two sources. Source number one are dietary sources. So we can ingest protein, break down the protein into amino acids, and then use the amino acids for some type of process.