Copolymers are polymers formed by the polymerization of two or more different monomers, resulting in a chain with varying properties. They can be designed for specific applications by altering the ratio and arrangement of monomers, like alternating, random, block, or graft copolymers. These variations influence characteristics like strength, flexibility, chemical resistance, and transparency. Common examples include styrene-butadiene rubber (SBR) used in tires and ethylene-vinyl acetate (EVA) for adhesives.