A polymer chain is a fundamental structure consisting of many repeating structural units, known as monomers, linked together through covalent or non-covalent bonds. These chains can range vastly in length and complexity, forming the basis of both biological macromolecules and synthetic materials. In chemistry, the process of forming these long chains is called polymerization. The properties of the resulting material or biomolecule—such as strength, flexibility, or charge distribution—are directly determined by the nature of the constituent monomers and the regularity of the linkages between them. Understanding chain formation and the forces governing its stability is essential for fields ranging from material science to biochemistry.