Collagen constitutes the most abundant proteins found in the body. The collagen All collagens contain greater or lesser stretches of triple helix. Collagens are deposited in the extracellular matrix where most of them form supramolecular assemblies. They interact with cells via several receptor families and regulate their proliferation, migration, and differentiation. Some collagens have a restricted tissue distribution and hence specific biological functions. As collagen forms building block of body structures, any defect in it causes various disorders. Thus this book discuss the role of collagen in health as well as disease.