Basic protein structure is briefly reviewed. Important aspects of proteins that are discussed include their basic chemical composition, their great diversity of structure, their large size and molecular weight, and their charged nature. Because the large molecular size of proteins, chemists have centered their attention on the relatively low molecular weight amino acids obtained when a protein is subjected to hydrolysis. Proteins are made up of over 20 individual amino acids. The general structure of amino acids (which are almost all alpha-amino carboxylic acids) is outlined. It is explained that the covalent bonding of the atoms which form the amino acids and the amino acids which form the protein totally determine the function of the protein. This is illustrated by a short review of fibrous proteins.