Secondary structure of protein refers to local folded structures that form within a polypeptide due to interactions between atoms of the backbone. They are found to exist in two different types of structures α–helix and β– pleated sheet structures. This structure arises due to the regular folding of the backbone of the polypeptide chain due to hydrogen bonding between −CO group and −NH groups of the peptide bond. Tertiary Structure of Protein arises from further folding of the secondary structure of the protein. H-bonds, electrostatic forces, disulphide linkages, and Vander Waals forces stabilise this structure. The tertiary structure of proteins represents overall folding of the polypeptide chains, further folding of the secondary structure.