The building blocks of proteins are known as amino acids. These organic compounds contain an amino group, a carboxyl group, and a unique side chain. There are 20 standard amino acids that combine in various sequences to form proteins, which play critical roles in biological processes such as catalysis, structure, signaling, and transport. The specific sequence and chemical properties of amino acids determine a protein's structure and function. Understanding amino acids is fundamental in fields like biochemistry and molecular biology.