  In this paper we review the recent extraordinary progress in the development
of a new quantum standard for resistance based on graphene. We discuss the
unique properties of this material system relating to resistance metrology and
discuss results of the recent highest-ever precision direct comparison of the
Hall resistance between graphene and traditional GaAs. We mainly focus our
review on graphene expitaxially grown on SiC, a system which so far resulted in
the best results. We also brie y discuss progress in the two other graphene
material systems, exfoliated graphene and chemical vapour deposition graphene,
and make a critical comparison with SiC graphene. Finally we discuss other
possible applications of graphene in metrology.
