This review explores some of the detail behind the type of polymers used in asphalt, why they are used, where they are used in terms of applications and the benefits they offer to industry and the road user. In particular the reader will understand how polymers can be used to enhance the functionality of asphalt, i.e., to overcome deterioration mechanisms by enhancing asphalt stiffness, flexibility or making it more resistant to deformation (rutting) caused by traffic. An indexed section containing several hundred key references and abstracts selected from the Polymer Library supports this review.