Graphene, a two-dimensional lattice of carbon atoms, has attracted enormous interest from a broad base of the research community for more than a decade. Graphene nanoribbons (GNRs), narrow strips of quasi one-dimensional graphene, possess complementary features relative to their two-dimensional counterpart of graphene sheets. Based on theoretical calculations, the electrical properties of GNRs can be controlled by the width and edge configuration, and they can vary from metallic to semiconducting.