Amino acids are the molecular components of proteins, the very structure of proteins, the way our body breaks them down to digest and assimilate them. A protein is nothing more than a collection of amino acids. Their importance in muscle building is undeniable. There are 20 known amino acids, 8 of which are essential. Essential means that the body must obtain them as they are through food (or protein powder) and is not able to synthesize them on its own.
Our bodies have a constant need for amino acids simply to function and renew their cells.
Everyone, whether an athlete or not, needs them, but this is even more true for those who train intensely.

To grow, muscles must synthesize more protein than they break down. This is made possible by sufficient protein intake: the amount of protein consumed exceeds the amount of protein destroyed, which is known as positive nitrogen balance.

There are 20 basic amino acids mentioned in the genetic code. These are:
Aspartic acid, glutamic acid, alanine, arginine,
asparagine, cystine, glutamine, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tyrosine, tryptophan, and valine.

Of these 20, 8 are considered essential. These are: isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.

The others are non-essential, which means that the body can obtain these amino acids from food or produce them itself (by synthesizing them from other amino acids).

Three basic non-essential amino acids may be essential in certain cases.

In infants, for example, histidine and arginine are essential. Glutamine becomes essential in patients suffering from trauma.