Protein is essential in the building and repairing of body tissues in human beings and animals. Protein is needed to create enzymes and hormones. Without protein building of blood, cartilage, bones and skin will not be possible. Proteins are more of amino acids.
There are 4 major types of proteins namely: Primary Structure, Secondary Structure , Tertiary Structure and Quaternary Structure. 
Source of protein: The major source of protein is from food which we take in daily basis. Food like meat, eggs, milk and fish. Taking the right quantity of protein for your body is always advised.