 Collagens are the most abundant proteins in vertebrates, making up some 30% of all proteins in the human body.Based on their molecular structures, collagen proteins are divided into two main classes – fibril-forming (or "fibrillar") collagens and non-fibril-forming ("non-fibrillar") collagens – which are further divided into 28 different types (as of 2017), based on individual structures and functions that the protein specifically has in the body.Fibrillar collagen, producing the three-dimensional frameworks in different tissues and organs, derived from a single common ancestor during evolution.