A polymer derived from more than one species of monomer.Note: Copolymers that are obtained by copolymerization of two monomer species are sometimes termed bipolymers, those obtained from three monomers terpolymers, those obtained from four monomers quaterpolymers, etc. Alternating copolymers: A copolymer consisting of macromolecules comprising two species of monomeric units in alternating sequence.Note: An alternating copolymer may be considered as a homopolymer derived from an implicit or hypothetical monomer.Block copolymers: A portion of a macromolecule, comprising many constitutional units, that has at least one feature which is not present in the adjacent portions.Graft macromolecule: A macromolecule with one or more species of block connected to the main chain as side-chains, these side-chains having constitutional or configurational features that differ from those in the main chain.When two or more different monomers unite together to polymerize, their result is called as copolymer and its process is called copolymerization.Commercially relevant copolymers include acrylonitrile butadiene styrene (ABS), styrene/butadiene co-polymer (SBR), nitrile rubber, styrene-acrylonitrile, styrene-isoprene-styrene (SIS) and ethylene-vinyl acetate.